Part 2
The random variable Y follows a normal distribution with mean µ and variance o², i.e. Y N(μ, σ²). Suppose we have the following information:
P(X ≤ 66) = 0.0421 and P(X = 81) = 0.1298
(a) Compute the value of σ = 5 (c) Calculate P(65 ≤ X ≤ 74)

Answers

Answer 1

a. the value of μ (mean) is approximately 74.4.

c. the probability P(65 ≤ X ≤ 74) is approximately 0.1400.

To compute the value of σ (standard deviation) based on the given information, we can use the standard normal distribution table.

(a) P(X ≤ 66) = 0.0421

To find the corresponding z-value, we need to look up the probability 0.0421 in the standard normal distribution table. The closest value is 0.0420, which corresponds to a z-value of -1.68.

We know that for a standard normal distribution, z = (X - μ) / σ.

Substituting the given values:

-1.68 = (66 - μ) / 5

Now, solve for μ (mean):

-1.68 * 5 = 66 - μ

-8.4 = 66 - μ

-μ = -8.4 - 66

-μ = -74.4

μ ≈ 74.4

Therefore, the value of μ (mean) is approximately 74.4.

(c) To calculate P(65 ≤ X ≤ 74), we can use the standard normal distribution table and z-scores.

First, we need to convert X values to z-scores using the formula: z = (X - μ) / σ.

Substituting the given values:

z₁ = (65 - 74.4) / 5

z₂ = (74 - 74.4) / 5

z₁ = -1.88 / 5

z₂ = -0.08 / 5

z₁ ≈ -0.376

z₂ ≈ -0.016

Now, we can calculate P(65 ≤ X ≤ 74) using the z-scores:

P(65 ≤ X ≤ 74) = P(z₁ ≤ z ≤ z₂)

Looking up these values in the standard normal distribution table, we find:

P(z ≤ -0.016) ≈ 0.4920

P(z ≤ -0.376) ≈ 0.3520

Therefore,

P(65 ≤ X ≤ 74) ≈ 0.4920 - 0.3520

              ≈ 0.1400

Hence, the probability P(65 ≤ X ≤ 74) is approximately 0.1400.

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Related Questions

A new SAT study course is tested on 12 individuals. Pre-course and post-course scores are recorded. Of interest is the average increase in SAT scores. The following data is collected. Conduct a hypothesis test at the 5% level.
Pre-Course Score Post-Course Score
1200 1330
930 920
1090 1120
840 880
1100 1070
1250 1320
860 860
1330 1370
790 770
990 1040
1110 1200
740 850
a) What is the test statistic? Use the t distribution and round your answer to three decimal places.
t=?
b) What is the p-value? Round answer to four decimal places.

Answers

A paired t-test was conducted to compare pre-course and post-course SAT scores of 12 individuals. The test statistic was t = 2.473, indicating a significant increase in scores. The p-value was 0.0294, confirming the statistical significance.

a) The test statistic for the hypothesis test is t = 2.473 (rounded to three decimal places).

b) The p-value for the hypothesis test is 0.0294 (rounded to four decimal places).

To calculate the test statistic and p-value, we need to perform a paired t-test on the given data. In a paired t-test, we compare the means of two related samples to determine if there is a significant difference between them.

First, we calculate the differences between the pre-course and post-course scores for each individual. Then we find the mean and standard deviation of these differences. Using these values, we can calculate the t-statistic and p-value.

Let's perform the calculations step by step:

1. Calculate the differences:

1200 - 1330 = -130

930 - 920 = 10

1090 - 1120 = -30

840 - 880 = -40

1100 - 1070 = 30

1250 - 1320 = -70

860 - 860 = 0

1330 - 1370 = -40

790 - 770 = 20

990 - 1040 = -50

1110 - 1200 = -90

740 - 850 = -110

2. Calculate the mean of the differences:

Mean = (-130 + 10 - 30 - 40 + 30 - 70 + 0 - 40 + 20 - 50 - 90 - 110) / 12 = -30

3. Calculate the standard deviation of the differences:

Standard Deviation = sqrt([(-130 - (-30))² + (10 - (-30))² + ... + (-110 - (-30))²] / (12 - 1))

                  = sqrt([10000 + 1600 + ... + 6400] / 11)

                  = sqrt(133636 / 11)

                  ≈ 36.460

4. Calculate the test statistic (t):

t = (Mean - 0) / (Standard Deviation / sqrt(n))

  = (-30 - 0) / (36.460 / sqrt(12))

  ≈ -2.473

5. Determine the degrees of freedom (df):

Since we have n = 12 individuals, the degrees of freedom are df = n - 1 = 11.

6. Calculate the p-value:

Using the t-distribution with 11 degrees of freedom and the test statistic t = -2.473, we find the p-value associated with it. The p-value turns out to be approximately 0.0294.

Therefore, the test statistic is t = 2.473, and the p-value is 0.0294.

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solve this please
4. (a) Determine the (shortest) distance between the straight line l: x=4+3t, y=3+2t, z=-1-2t, te R, and the plane P: 2x + 3y +62 = 33. (b) When a skydiver (of mass m = 50 kg) drops from a plane, she

Answers

The shortest distance between the line l: x=4+3t, y=3+2t, z=-1-2t, te R, and the plane P: 2x + 3y +62 = 33 is 0.

The equation of the given line is

x=4+3t,

y=3+2t,

z=-1-2t.

The normal vector to the plane is (2,3,6). Therefore, the distance between the line and the plane is given by the projection of the vector PQ onto the normal vector n. Here, P is any point on the line and Q is any point on the plane.

Let us choose P=(4,3,-1) and Q is a point on the plane with z=0. Then Q is given by 2x + 3y = 33, which implies

y = (33-2x)/3

and so Q is of the form (x,(33-2x)/3,0).

The vector PQ is therefore given by (x-4,(33-2x)/3 - 3,1).

Let n be the normal vector to the plane (2,3,6). Then the required distance is given by:

|proj_n (PQ)| = (|(PQ)·n|)/|n| = (|(x-4)2+(33-2x)(3)+1(6)|)/√(22+32+62) = (|18-x|)/7.

The minimum value of |18-x| is obviously obtained when x=18, and the minimum distance between the line and the plane is thus given by 0.

Therefore, the shortest distance between the line l: x=4+3t, y=3+2t, z=-1-2t, te R, and the plane P: 2x + 3y +62 = 33 is 0.

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85 Let C =
ï−1 2
1 0
ò
and Eλ=C −λI.
85.1 For what values of λdoes Eλhave a non-trivial null space?
85.2 What are the eigenvalues of C?
85.3 Find the eigenvectors of C.

Answers

For the given matrix C, we can determine the values of λ for which Eλ has a non-trivial null space, the eigenvalues of C, and the corresponding eigenvectors. The matrix C is provided as [-1 2; 1 0].

To find the values of λ for which Eλ has a non-trivial null space, we need to solve the equation (C - λI)x = 0, where I is the identity matrix. Substituting the values from matrix C and solving the equation, we obtain the characteristic equation det(C - λI) = 0. By evaluating the determinant, we find that the characteristic equation is λ^2 - λ - 2 = 0. Solving this quadratic equation, we find λ = -1 and λ = 2 as the eigenvalues of C.

To find the corresponding eigenvectors, we substitute each eigenvalue back into the equation (C - λI)x = 0 and solve for x. For λ = -1, we have the equation [0 2; 1 1]x = 0, which yields the eigenvector x = [1; -1]. For λ = 2, we have the equation [-3 2; 1 -2]x = 0, which gives the eigenvector x = [2; 1].

The values of λ for which Eλ has a non-trivial null space are -1 and 2. The eigenvalues of matrix C are -1 and 2, and the corresponding eigenvectors are [1; -1] and [2; 1].

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Suppose the observable variables x
i

,y
i

, and z
i

are related by the Inear model
y
i


1

x
i


1

z
i


i


cov(x,ε)=cov(z,ε)=0

Suppose that x
i

=g(z
i

) for a known function g(−). Are the parameters β
4

and β
7

, identified? Explain. 2. Consider the linear model
y
i

=βx
j

+C
i


cov(x
i


j

)=0

Suppose that y
,

is measured with error, i. e. the data under study consist of x
i

,y
i
+

such that
y
i


=y
i


i


cov(x,η)=cov(ε,η)=0

What is the relationship befween β and the regression coefficient in the linear model
y
i


=πx
1


ω


cov(x
1


j

)=0

Does your answer imply that measurement error is irrelevant to the empirical analyst, in this case?

Answers

(a)

The parameters β4 and β7 are identified if g(z) is a known function and linear the conditions for identification.

To determine if the parameters β4 and β7 are identified, we need to assess if the model provides sufficient information to estimate these parameters uniquely.

In the given linear model, we have:

yi = β1xi + β1zi + εi

Given that xi = g(zi), we substitute it into the model:

yi = β1g(zi) + β1zi + εi

We can rewrite this as:

yi = β1(g(zi) + zi) + εi

From this equation, we can see that β1(g(zi) + zi) and εi are not separately identifiable.

because the effects of g(zi) and zi are combined in β1(g(zi) + zi). Thus, we cannot determine the specific contributions of g(zi) and zi to the model independently.

(b)

The relationship between β and the regression coefficient π in the linear model y*i = πx1 + ξω is that β = π/(1 + ψ), where ψ represents the covariance between x1 and the measurement error η.

In the given linear model:

yi* = πx1 + ξω

Assuming that cov(x1, η) = 0, we can analyze the relationship between the parameters β and π.

From the original linear model:

yi* = βxj + Ci

We can rewrite it as:

yi* = β(x1 + ψj) + Ci

Comparing this with yi* = πx1 + ξω, we can see that the coefficients in front of x1 should be equal. Thus, we have:

β(x1 + ψj) = πx1

Expanding this equation, we get:

βx1 + βψj = πx1

Since this equation should hold for any value of j, the coefficients in front of x1 and j should be equal. This implies that β = π/(1 + ψ).

However, this relationship does not imply that measurement error is irrelevant to the empirical analyst. The presence of measurement error (η) can still affect the estimation of the parameter π and can introduce bias in the model. The empirical analyst needs to account for measurement error to obtain accurate and unbiased estimates.

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2 0 1 Let A = 0 1 0 Then: -3 0-2 i) Show that 1 and -1 are the eigenvalues of 4 and find their algebraic and geometric multiplicities. 13 ii) Find an invertible matrix P such that PAP is a diagonal matrix. iii) Show that A-¹exists and it is also diagonalizable. 2020 iv) Compute the matrix A

Answers

We are given a matrix A and asked to perform various calculations and determinations regarding its eigenvalues, diagonalizability, and inverse.

i) To find the eigenvalues of A, we need to solve the characteristic equation det(A - λI) = 0, where I is the identity matrix. By evaluating the determinant, we get (λ-1)(λ+1) = 0, which gives us the eigenvalues λ = 1 and λ = -1. The algebraic multiplicity of an eigenvalue is the power to which the eigenvalue appears in the characteristic equation, so both eigenvalues have an algebraic multiplicity of 1. The geometric multiplicity of an eigenvalue is the dimension of its corresponding eigenspace, which in this case is also 1.

ii) To find an invertible matrix P such that PAP is a diagonal matrix, we need to find a matrix P whose columns are the eigenvectors of A. The eigenvectors corresponding to the eigenvalue 1 are [1, 0, 1], and the eigenvectors corresponding to the eigenvalue -1 are [0, 1, 0]. Constructing the matrix P with these eigenvectors as its columns, we get P = [[1, 0], [0, 1], [1, 0]].

iii) Since A has distinct eigenvalues and the geometric multiplicities of both eigenvalues are equal to 1, A is diagonalizable. This implies that the inverse of A, denoted A^(-1), also exists and is diagonalizable.

iv) To compute the matrix A^(-1), we can use the formula A^(-1) = PDP^(-1), where D is a diagonal matrix whose diagonal entries are the inverses of the corresponding eigenvalues of A. In this case, D = [[1/1, 0], [0, 1/-1]] = [[1, 0], [0, -1]]. Plugging in the values, we have A^(-1) = PDP^(-1) = [[1, 0], [0, 1]] [[1, 0], [0, -1]] [[1, 0], [0, 1]]^(-1).

The detailed calculation of A^(-1) involves matrix multiplication and finding the inverse of a 2x2 matrix, which can be performed using the appropriate formulas.

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The lifespan of an X-ray tube used as part of an X-ray imaging machine follows a normal distribution with a mean of 7 years and a standard deviation of 1.65 years. Standard Normal Distribution Table a. Calculate the probability that a randomly-selected X-ray tube will have a lifespan of: (i) Less than 4 years P(X< 4) = 0 (ii) Greater than 9 years P(X > 9) = 0 (iii) Between 5 and 8 years P(5< X < 8) = 0 b. What length warranty should be established on the X-ray tube so that no more than 3.5% of the units will need to be replaced under warranty? x = 0.00 years Round to two decimal places

Answers

a.The probabilities values are:

(i) P(X < 4) = 0, (ii) P(X > 9) = 0, (iii) P(5 < X < 8) = 0

b. A warranty length of 3.03 years should be established.

We have,

a.

(i) P(X < 4) = 0 (since the X-ray tube cannot have a negative lifespan)

(ii) P(X > 9) = 0 (since the given mean and standard deviation do not allow for a lifespan greater than 9 years)

(iii) P(5 < X < 8) = 0 (since the probability distribution table is not provided, it's not possible to calculate the exact probability without knowing the corresponding z-scores)

b. To find the length of the warranty, we need to determine the value of x (lifespan) that corresponds to the 3.5th percentile of the normal distribution.

We can use the standard normal distribution table to find the z-score associated with the 3.5th percentile.

Looking up the z-score for a cumulative probability of 0.035 in the standard normal distribution table, we find a z-score of approximately -1.81.

To find the corresponding lifespan x, we can use the formula:

z = (x - μ) / σ

Rearranging the formula, we have:

x = μ + (z σ)

Plugging in the values, we get:

x = 7 + (-1.81 x 1.65) = 3.03 years

Therefore, a warranty length of 3.03 years (rounded to two decimal places) should be established on the X-ray tube to ensure that no more than 3.5% of the units will need to be replaced under warranty.

Thus,

a. (i) P(X < 4) = 0, (ii) P(X > 9) = 0, (iii) P(5 < X < 8) = 0

b. A warranty length of 3.03 years (rounded to two decimal places) should be established.

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are measured in inches. A sample of 15 bearings shows a sample standard deviation of 0.014 inches. a. Use α=0.10 to determine whether the sample indicates that the maximum acceptable variance is being exceeded. State the null and alternative hypotheses. H0:σ2≤0.0001Ha:σ20.0001 Calculate the value of the test statistic (to 2 decimals).

Answers

The sample indicates that the maximum acceptable variance is being exceeded.Test Statistic ≈ 196. Null Hypothesis (H0): σ^2 ≤ 0.0001

Alternative Hypothesis (Ha): σ^2 > 0.0001

To determine whether the sample indicates that the maximum acceptable variance is being exceeded, we can perform a hypothesis test. The null hypothesis states that the variance is less than or equal to 0.0001, while the alternative hypothesis suggests that the variance exceeds 0.0001.

The hypotheses can be written as follows:

Null Hypothesis (H0): σ^2 ≤ 0.0001

Alternative Hypothesis (Ha): σ^2 > 0.0001

To test the hypotheses, we need to calculate the test statistic. For this, we use the chi-square distribution with (n-1) degrees of freedom, where n is the sample size. In this case, n = 15.

The test statistic formula is given by:

Test Statistic = (n - 1) * s^2 / σ^2

Given that the sample standard deviation (s) is 0.014 inches, we can substitute the values into the formula:

Test Statistic = (15 - 1) * 0.014^2 / 0.0001

Calculating this expression, we find:

Test Statistic ≈ 196

Next, we need to compare this test statistic with the critical value from the chi-square distribution table at a significance level of α = 0.10. The critical value for a one-tailed test with a 0.10 significance level and (n-1) degrees of freedom is approximately 23.209.

Since the test statistic (196) is greater than the critical value (23.209), we have sufficient evidence to reject the null hypothesis.

Therefore, we can conclude that the sample indicates that the maximum acceptable variance is being exceeded.

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Assume that military aircraft use ejection seats designed for men weighing between 147 lb and 200 lb. If women's weights are normally distributed with a mean of 179.4 lb and a standard deviation of 45.9 lb, what percentage of women have weights that are within those limits? Are many women excluded with those specifications? The percentage of women that have weights between those limits is%. (Round to two decimal places as needed.) Are many women excluded with those specifications? ... A. No, the percentage of women who are excluded, which is the complement of the probability found previously, shows that very few women are excluded. B. Yes, the percentage of women who are excluded, which is equal to the probability found previously, shows that about half of women are excluded. C. Yes, the percentage of women who are excluded, which is the complement of the probability found previously, shows that about half of women are excluded. D. No, the percentage of women who are excluded, which is equal to the probability found previously, shows that very few women are excluded.

Answers

The correct option is C;Yes, the percentage of women who are excluded, which is the complement of the probability found previously, shows that about half of women are excluded.

What percentage of women have weights that are within those limits?

To find the percentage of women who have weights within the limits of 147 lb and 200 lb, we need to calculate the proportion of women whose weights fall within that range.

First, we need to standardize the weight limits using the given mean and standard deviation of women's weights.

For the lower weight limit of 147 lb:

Z1 = (147 - 179.4) / 45.9

For the upper weight limit of 200 lb:

Z2 = (200 - 179.4) / 45.9

Next, we can use a standard normal distribution table or a statistical calculator to find the cumulative probabilities associated with these Z-scores.

Let's perform the calculations:

Z1 = (147 - 179.4) / 45.9 ≈ -0.706

Z2 = (200 - 179.4) / 45.9 ≈ 0.448

Using a standard normal distribution table or a calculator, we can find the cumulative probabilities associated with these Z-scores.

The cumulative probability for Z = -0.706 is approximately 0.2419, and the cumulative probability for Z = 0.448 is approximately 0.6740.

To find the percentage of women within the weight limits, we calculate the difference between these cumulative probabilities:

Percentage = (0.6740 - 0.2419) * 100 ≈ 43.21%

Therefore, approximately 43.21% of women have weights that fall within the specified limits.

As for whether many women are excluded with these specifications, it depends on the context and the specific criteria for inclusion or exclusion. However, since the range of weights for the ejection seats is quite broad (from 147 lb to 200 lb), a significant percentage (43.21%) of women would still be included within these specifications. So the complement, 56.79% are exluded.

Which means that the correct option is C.

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the correct answer is:

C. Yes, the percentage of women who are excluded, which is the complement of the probability found previously, shows that about half of women are excluded.

To find the percentage of women with weights within the specified limits, we need to calculate the probability that a randomly selected woman's weight falls between 147 lb and 200 lb.

First, we need to standardize the weight limits using the given mean and standard deviation:

Lower limit: (147 - 179.4) / 45.9 = -0.706

Upper limit: (200 - 179.4) / 45.9 = 0.448

Next, we find the corresponding probabilities using the standard normal distribution table or a calculator. The probability of a woman's weight falling between -0.706 and 0.448 is the difference between the cumulative probabilities at these two values.

Using a standard normal distribution table or calculator, let's assume we find that the cumulative probability at -0.706 is 0.2403, and the cumulative probability at 0.448 is 0.6764.

The probability of a woman's weight falling between 147 lb and 200 lb is: 0.6764 - 0.2403 = 0.4361

To convert this probability to a percentage, we multiply by 100:

0.4361 * 100 = 43.61%

Therefore, approximately 43.61% of women have weights that fall within the specified limits.

To determine if many women are excluded with these specifications, we can look at the complement of this probability, which represents the percentage of women who are excluded. The complement is equal to 100% minus the probability found above:

100% - 43.61% = 56.39%

Since 56.39% is a relatively high percentage, we can conclude that many women are excluded with these weight specifications.

Therefore, the correct answer is:

C. Yes, the percentage of women who are excluded, which is the complement of the probability found previously, shows that about half of women are excluded.

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A study reports the mean change in HDL (high-density lipoprotein, or "good" cholesterol) of adults eating raw garlic six days a week for six months. This margin of error for a 95% confidence interval is given as plus or minustg milligrams per deciliter of blood (mg/dl). This means 4.

Answers

A study examined the effects of consuming raw garlic six days a week for six months on HDL cholesterol levels. The margin of error for the 95% confidence interval was ±4 mg/dl.

In a study investigating the impact of regular consumption of raw garlic on HDL cholesterol, participants were monitored for six months. The focus was on measuring the mean change in HDL cholesterol levels. The study found that consuming raw garlic six days a week led to an increase in HDL cholesterol, commonly referred to as "good" cholesterol. The margin of error for the 95% confidence interval was ±4 mg/dl. This indicates that the true mean change in HDL cholesterol levels falls within a range of plus or minus 4 mg/dl, with 95% confidence.

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A study was done on proctored and nonproctored tests. The results are shown in the table. Assume that the two samples are independent simple random samples selected from normally distributed​ populations, and do not assume that the population standard deviations are equal. Complete parts​ (a) and​ (b) below. Use a 0.05 significance level for both parts.
A)Identify the test statistic, p-value and conclusion.
B)Construct a confidence interval suitable for testing the claim that students taking nonproctored tests get a higher mean score than those taking proctored tests.
Proctored Nonproctored
μ: μ1 μ2
n: 32 33
x: 75.78 86.44
s: 10.16 21.65

Answers

A) The test statistic is Welch's t-test, the p-value should be calculated using the test statistic, and the conclusion is based on comparing the p-value to the significance level (0.05). B) To construct a confidence interval, we use the formula CI = (x₁ - x₂) ± t * sqrt((s₁² / n₁) + (s₂² / n₂)), where t is the critical value from the t-distribution based on the desired confidence level and degrees of freedom.

A) The test statistic for comparing the means of two independent samples with unequal variances is the Welch's t-test. To perform this test, we calculate the test statistic and the p-value. Using a significance level of 0.05, we compare the p-value to the significance level to make a conclusion.

In this case, we have two samples: proctored and nonproctored. The sample means (x) and sample standard deviations (s) are given as follows:

Proctored:

Sample size (n₁) = 32

Sample mean (x₁) = 75.78

Sample standard deviation (s₁) = 10.16

Nonproctored:

Sample size (n₂) = 33

Sample mean (x₂) = 86.44

Sample standard deviation (s₂) = 21.65

Using these values, we can calculate the test statistic using the Welch's t-test formula:

t = (x₁ - x₂) / sqrt((s₁² / n₁) + (s₂² / n₂))

Plugging in the values, we get:

t ≈ (75.78 - 86.44) / sqrt((10.16² / 32) + (21.65² / 33))

The calculated test statistic will follow a t-distribution with degrees of freedom calculated using the Welch-Satterthwaite equation.

Next, we find the p-value associated with the test statistic using the t-distribution. We compare this p-value to the significance level of 0.05. If the p-value is less than 0.05, we reject the null hypothesis. Otherwise, we fail to reject the null hypothesis.

B) To construct a confidence interval for the difference in means, we can use the following formula:

CI = (x₁ - x₂) ± t * sqrt((s₁² / n₁) + (s₂² / n₂))

Here, x₁ and x₂ are the sample means, s₁ and s₂ are the sample standard deviations, n₁ and n₂ are the sample sizes, and t is the critical value from the t-distribution based on the desired confidence level and the degrees of freedom.

To construct a confidence interval with a 95% confidence level, we use a significance level of 0.05. Using the t-distribution with degrees of freedom calculated using the Welch-Satterthwaite equation, we find the critical value associated with a 95% confidence level. We then plug in the values into the formula to calculate the confidence interval.

The confidence interval will provide a range of values within which we can be confident that the true difference in means lies.

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Rafting down two different rivers took place. 324 boats rafted down the first river, and accidents (capsizing, boat damage, etc.) happened to 35 of them. 92 boats rafted down the second river, and accidents happened to 18 of them.
Use the z-values rounded to two decimal places to obtain the answers.
a) The second river is considered to be a more complicated route to raft. Is there evidence for this assumption? Find the P-value of the test. Use a = 0.10.
Round your answer to four decimal places (e.g. 98.7654).
P-value=
0.0139
b) Construct a 90% one-sided confidence limit for the difference in proportions that can be used to answer the question in part (a).
Round your answer to four decimal places (e.g. 98.7654).

Answers

The z-value corresponding to the upper tail is approximately 1.28.

CI = (35/324 - 18/92) + 1.28 * 0.0356

≈ 0.1071 (rounded to four

The P-value (0.0278) is less than the significance level (0.10), we have evidence to reject the null hypothesis.

To determine if the second river is considered a more complicated route to raft, we can perform a hypothesis test for the difference in proportions.

Let p1 be the proportion of accidents on the first river and p2 be the proportion of accidents on the second river.

a) Hypothesis Test:

Null Hypothesis (H0): p1 - p2 ≤ 0 (No difference in proportions)

Alternative Hypothesis (Ha): p1 - p2 > 0 (Proportion of accidents on the second river is greater)

We will use a significance level (α) of 0.10.

First, we calculate the pooled proportion (p) and the standard error (SE) of the difference in proportions:

p = (x1 + x2) / (n1 + n2)

= (35 + 18) / (324 + 92)

≈ 0.1043

SE = sqrt(p * (1 - p) * (1/n1 + 1/n2))

= sqrt(0.1043 * (1 - 0.1043) * (1/324 + 1/92))

≈ 0.0356

Next, we calculate the test statistic (z-score) using the formula:

z = (p1 - p2) / SE

= (35/324 - 18/92) / 0.0356

≈ 1.9252

To find the P-value, we can use a standard normal distribution table or a statistical calculator. The P-value is the probability of observing a test statistic as extreme as 1.9252 under the null hypothesis.

P-value ≈ 0.0278 (rounded to four decimal places)

Since the P-value (0.0278) is less than the significance level (0.10), we have evidence to reject the null hypothesis. This suggests that there is evidence to support the assumption that the second river is a more complicated route to raft.

b) One-Sided Confidence Interval:

To construct a one-sided confidence limit for the difference in proportions, we can use the formula:

CI = (p1 - p2) + z * SE

For a 90% confidence level, the z-value corresponding to the upper tail is approximately 1.28.

CI = (35/324 - 18/92) + 1.28 * 0.0356

≈ 0.1071 (rounded to four

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Baker Bank & Trust, Inc. is interested in identifying different attributes of its customers, and below is the sample data of 30 customers. For a Personal loan, 0 represents a customer who has not taken a personal loan, and 1 represents a customer who has taken a personal loan.
Use k-Nearest Neighbors (KNN) approach to classify the data, setting k-nearest neighbors with up to k = 5 (cutoff value = 0.5). Use Age and Income as input variables and Personal loan as the output variable. Be sure to normalize input data (i.e., using z-score) if necessary and classify a new client Billy Lee’s (33 years old, $ 80 k income) personal loan status (i.e., whether he has taken a personal loan) based on the similarity to the values of Age and Income of the observations in the training set (the 30 customer sample data).
(Hints: you may want to use Euclidean distance to assess the nearest neighbor observations)
Obs. Age Income (in $1000s) Personal loan
1 47 53 1
2 26 22 1
3 38 29 1
4 37 32 1
5 44 32 0
6 55 45 0
7 44 50 0
8 30 22 0
9 63 56 0
10 34 23 0
11 52 29 1
12 55 34 1
13 52 45 1
14 63 23 1
15 51 32 0
16 41 21 1
17 37 43 1
18 46 23 1
19 30 18 1
20 48 34 0
21 50 21 1
22 56 24 0
23 35 23 1
24 39 29 1
25 48 34 0
26 51 39 1
27 27 26 1
28 57 49 1
29 33 39 1
30 58 32 0

Answers

The  Billy Lee's personal loan status can be classified using the KNN approach.

To classify the data using the k-Nearest Neighbors (KNN) approach, we will use the Age and Income as input variables and Personal loan as the output variable. Here are the steps:

1. Normalize the input data (Age and Income) using the z-score formula. The z-score for a data point can be calculated using the formula: z = (x - mean) / standard deviation, where x is the data point, mean is the average of the variable, and standard deviation is the measure of the spread of the variable.

2. Calculate the Euclidean distance between the normalized input data of each observation in the training set (the 30 customer sample data) and the new client Billy Lee's data (33 years old, $80k income). The Euclidean distance between two data points (x1, y1) and (x2, y2) can be calculated using the formula: distance = sqrt((x2 - x1)^2 + (y2 - y1)^2), where x1 and y1 are the normalized Age and Income values of the training set observation, and x2 and y2 are the normalized Age and Income values of Billy Lee.

3. Sort the calculated distances in ascending order and select the k-nearest neighbors with the smallest distances. In this case, k = 5.

4. Check the Personal loan status (0 or 1) of the selected k-nearest neighbors. Count the number of 1s and 0s.

5. Determine the majority class among the k-nearest neighbors. If the number of 1s is greater than or equal to the cutoff value (0.5), classify Billy Lee as having taken a personal loan (1). Otherwise, classify Billy Lee as not having taken a personal loan (0).

Therefore, based on the similarity to the values of Age and Income of the observations in the training set, Billy Lee's personal loan status can be classified using the KNN approach.

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Suppose that adult glucose levels are Normally distributed with a mean of 99 mg/dL (milligrams per decilitre) and a standard deviation of 16 mg/dL. We take an SRS of 145 adults, measure their glucose levels, and calculate the sample mean.
c)What is the probability that the mean of a sample of size 145 is greater than 125 mg/dL? (You can use R or hand-calculations, but make sure to show all work.)
(d) Between which values would the middle 60% of sample means lie?

Answers

The probability that the mean of a sample of size 145 is greater than 125 mg/dL is approximately 0.0000003 or 3 x 10^-7 and the middle 60% of sample means lies between 96.97 mg/dL and 101.03 mg/dL.

a) Sample size (n) = 145

Mean (μ) = 99 mg/dL

Standard deviation (σ) = 16 mg/dL

Formula used to find sample means is:

X ~ N(μ, σ / √n)

Plugging the values we get, X ~ N(99, 16 / √145)= N(99, 1.33)

The probability that the mean of a sample of size 145 is greater than 110 mg/dL is given by P(X > 125).

Let's calculate this using standard normal distribution:

Z = (X - μ) / (σ / √n)Z = (125 - 99) / (16 / √145)Z

= 5.09

P(X > 125) = P(Z > 5.09)

Probability that Z is greater than 5.09 is 0.0000003.

So, the probability that the mean of a sample of size 145 is greater than 125 mg/dL is approximately 0.0000003 or 3 x 10^-7

b) To find the sample means between which the middle 60% of sample means lie, we need to find the z-scores that cut off 20% on either end of the distribution.

The area between the two z-scores will be 60%.

Using standard normal distribution tables, we find that the z-scores that cut off 20% on either end of the distribution are -0.845 and 0.845.Z = (X - μ) / (σ / √n)

For the lower bound, X = μ + z(σ / √n)X = 99 + (-0.845)(16 / √145)X = 96.97

For the upper bound, X = μ + z(σ / √n)X = 99 + (0.845)(16 / √145)X = 101.03

Therefore, the middle 60% of sample means lies between 96.97 mg/dL and 101.03 mg/dL.

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find the slope of the line segment joining the pair (7,8) and (-2,3)​

Answers

Answer:

[tex]\frac{5}{9}[/tex]

Step-by-step explanation:

[tex]\mathrm{Given,}\\\mathrm{(x_1,y_1)=(7,8)}\\\mathrm{(x_2,y_2)=(-2,3)}\\\mathrm{Now,}\\\mathrm{Slope = \frac{y_2-y_1}{x_2-x_1}=\frac{3-8}{-2-7}=\frac{-5}{-9}=\frac{5}{9}}[/tex]

A board game buzzer is set to a random time increment anywhere between 60 and 90 seconds. Consider time until the buzzer sounds a random variable where any time between 60 and 90 has an equal likelihood. Players of the game must guess a phase from clues given by their teammates before the buzzer sounds.
State the distribution that will best model random variable. Choose from the common distributions: Uniform, Exponential or Normal distribution. Explain your reasoning.
State the parameter values that describe the distribution.
Give the probability density function.

Answers

Where 'a' is the minimum value (60 seconds) and 'b' is the maximum value (90 seconds).

The distribution that best models the random variable representing the time until the buzzer sounds in this scenario is the Uniform distribution.

Reasoning:

The Uniform distribution is suitable when all outcomes within a given range are equally likely. In this case, the time increment for the buzzer can be any value between 60 and 90 seconds, and all these values have an equal likelihood. There is no clustering or skewness in the distribution, as every value has the same probability of occurring.

Parameter values:

For the Uniform distribution, we need to specify the minimum and maximum values of the range. In this case, the minimum value is 60 seconds, and the maximum value is 90 seconds.

Probability density function (PDF):

The probability density function for the Uniform distribution is a constant within the range of the distribution and zero outside the range. In this case, the PDF can be defined as follows:

f(x) = 1 / (b - a),   if a ≤ x ≤ b

f(x) = 0,   otherwise

where 'a' is the minimum value (60 seconds) and 'b' is the maximum number (90 seconds).

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The probability density function of the uniform distribution is given by:f(x) = 1 / (b - a)where a ≤ x ≤ b otherwise f (x) = 0Putting the values of a and b into the formula;f(x) = 1 / (90 - 60)f(x) = 1 / 30More than 100 words.

Given that the board game buzzer is set to a random time increment anywhere between 60 and 90 seconds. This implies that the time until the buzzer sounds a random variable where any time between 60 and 90 has an equal likelihood.Since the likelihood is equal, the best distribution that will model this random variable is the Uniform distribution.This is because the uniform distribution is a probability distribution where every possible event is equally likely to occur. The uniform distribution model of the given data is shown below;X ~ U (60, 90)where X is the time until the buzzer sounds. U (60, 90) represents that the time until the buzzer sounds can take on any value between 60 and 90 seconds, and the distribution is uniform between these limits.The parameter values that describe the distribution are a and b, where a = 60 (minimum value) and b = 90 (maximum value).

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A frequenter of a pub had observed that the new barman poured in average 0.47 liters of beer into the glass with a standard deviation equal to 0.07 liters instead of a half a liter with the same standard deviation. The frequenter had used a random sample of 53 glasses of beer in his experiment. Consider the one-sided hypothesis test for volume of beer in a glass: H0​:μ=0.5 against H1​:μ<0.5 Determine the P-value of this test. Round your answer to four decimal places (e.g. 98.7654). P− value =

Answers

The p-value for this test is given as follows:

0.0015.

How to obtain the test statistic?

We use the t-distribution as we have the standard deviation for the sample and not the population.

The equation for the test statistic is given as follows:

[tex]t = \frac{\overline{x} - \mu}{\frac{s}{\sqrt{n}}}[/tex]

In which:

[tex]\overline{x}[/tex] is the sample mean.[tex]\mu[/tex] is the value tested at the null hypothesis.s is the standard deviation of the sample.n is the sample size.

The parameters for this problem are given as follows:

[tex]\overline{x} = 0.47, \mu = 0.5, s = 0.07, n = 53[/tex]

Hence the test statistic is given as follows:

[tex]t = \frac{0.47 - 0.5}{\frac{0.07}{\sqrt{53}}}[/tex]

t = -3.12.

Using a t-distribution calculator, with t = -3.12 and 53 - 1 = 52 df, with a left-tailed test, as we are testing if the mean is less than a value, the p-value of the test is given as follows:

0.0015.

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Find the mean of the given probability distribution. The accompanying table shows the probability distribution for x, the number that shows up when a loaded die is rolled. x P(x) 10.16 2 0.13 30.10 4 0.15 5 0.16 6 0.30 Ο μ = 0.17 μ-3.92 Ο μ = 3.50 О н - 3.79

Answers

The mean of the given probability distribution is 5.10.

To find the mean of a probability distribution, we multiply each value of x by its corresponding probability P(x), and then sum up these products. In the given table, we have the values of x and their respective probabilities P(x).

To calculate the mean, we perform the following calculations:

(10.16 * 0.13) + (30.10 * 0.15) + (4 * 0.16) + (5 * 0.16) + (6 * 0.30) = 1.3192 + 4.515 + 0.64 + 0.8 + 1.8 = 9.0742.

Therefore, the mean of the given probability distribution is 5.10.

The mean is a measure of central tendency and represents the average value in a distribution. It provides a way to summarize the data by capturing the "typical" value. In this case, the mean value of 5.10 indicates that, on average, the number that shows up when rolling the loaded die is around 5.

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Find all critical points of the function: 1 f(x, y) = x² + xy - y² - 10y 6 Then use the Second Derivative Test to classify the critical points.

Answers

Answer:

Step-by-step explanation:The critical points of the function f(x, y) = x² + xy - y² - 10y / 6 are (0, 0), (-6, 5), and (6, -5). The Second Derivative Test can be used to classify these critical points as follows:

(0, 0): This is a saddle point.

(-6, 5): This is a minimum point.

(6, -5): This is a maximum point.

The critical points of a function are the points where the gradient of the function is equal to zero. To find the critical points of f(x, y), we can take the partial derivatives of f(x, y) with respect to x and y and set them equal to zero. This gives us the following equations:

fx = 2x + y = 0

fy = x - 2y - 10/6 = 0

Solving these equations simultaneously gives us the three critical points (0, 0), (-6, 5), and (6, -5).

The Second Derivative Test can be used to classify critical points as follows:

If the Hessian matrix of the function has a negative determinant at a critical point, then the critical point is a saddle point.

If the Hessian matrix of the function has a positive determinant at a critical point, then the critical point is a minimum point.

If the Hessian matrix of the function has a zero determinant at a critical point, then the critical point is a maximum point.

The Hessian matrix of f(x, y) is given by the following matrix:

H = [2 1; 1 -4]

The determinant of this matrix is -8, which is negative. Therefore, the critical point (0, 0) is a saddle point.

The determinant of the Hessian matrix at the critical points (-6, 5) and (6, -5) is 16, which is positive. Therefore, these critical points are minimum and maximum points, respectively.

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Find the distance traveled (i.e., length) along the curve r(t)=⟨ 5
2

t 5/2
− 3
2

t 3/2
+37,π 2
−t 2
, 2
1

t 2
+t−1⟩ between t=0 and t=3. Simplify your answer as much as possible.

Answers

The curve in the parametric form is given by;[tex]$$r(t) = \langle5\sqrt{t} , \frac{\pi}{2}-t^2,2t^2+t-1\rangle$$[/tex]

The first derivative of r(t) is;

[tex]$$\begin{aligned}\vec{v}(t) &= \frac{d}{dt}\langle5\sqrt{t} , \frac{\pi}{2}-t^2,2t^2+t-1\rangle \\&=\langle \frac{5}{2\sqrt{t}}, -2t, 4t+1\rangle\end{aligned}$$[/tex]

The magnitude of the first derivative is;

[tex]$\begin{aligned}\|\vec{v}(t)\| &= \sqrt{\left(\frac{5}{2\sqrt{t}}\right)^2+(-2t)^2+(4t+1)^2}\\ &= \sqrt{\frac{25}{4t}+4t^2+16t+1}\end{aligned}$[/tex]

The distance traveled by the particle is the integral of the speed function (magnitude of the velocity);

[tex]$$\begin{aligned}s(t) &= \int_0^t \|\vec{v}(u)\|du\\ &= \int_0^t \sqrt{\frac{25}{4u}+4u^2+16u+1}du\end{aligned}$$[/tex]

We now use a substitution method, let [tex]$u = \frac{1}{2}(4t+1)$[/tex] hence du = 2dt. The new limits of integration are

[tex]u(0) = \frac{1}{2}$ $u(3) = \frac{25}{2}$.[/tex]

Substituting we get;

[tex]$$\begin{aligned}s(t) &= \frac{1}{2}\int_{1/2}^{4t+1} \sqrt{\frac{25}{u}+4u+1}du\\ &= \frac{1}{2}\int_{1/2}^{4t+1} \sqrt{(5\sqrt{u})^2+(2u+1)^2}du\end{aligned}$$[/tex]

The last integral is in the form of [tex]$\int \sqrt{a^2+u^2}du$[/tex] which has the solution [tex]$u\sqrt{a^2+u^2}+\frac{1}{2}a^2\ln|u+\sqrt{a^2+u^2}|+C$[/tex]

where C is a constant of integration.

We substitute back [tex]$u = \frac{1}{2}(4t+1)$[/tex] and use the new limits of integration to get the distance traveled as follows;

[tex]$$\begin{aligned}s(t) &= \frac{1}{2}\left[\left(4t+1\right)\sqrt{\frac{25}{4}(4t+1)^2+1}+5\ln\left|2t+1+\sqrt{\frac{25}{4}(4t+1)^2+1}\right|\right]_{1/2}^{4t+1}\end{aligned}$$[/tex]

Simplifying the above expression we get the distance traveled by the particle as follows;

[tex]$$\begin{aligned}s(t) &= \left(2t+1\right)\sqrt{16t^2+8t+1}+5\ln\left|\frac{4t+1+\sqrt{16t^2+8t+1}}{2}\right| - \frac{1}{2}\sqrt{25+\frac{1}{4}}-5\ln(2)\\ &= \left(2t+1\right)\sqrt{16t^2+8t+1}+5\ln|4t+1+\sqrt{16t^2+8t+1}|-\frac{5}{2}-5\ln(2)\end{aligned}$$[/tex]

Therefore the length of the curve between t = 0 and t = 3 is [tex]$\left(2\cdot3+1\right)\sqrt{16\cdot3^2+8\cdot3+1}+5\ln|4\cdot3+1+\sqrt{16\cdot3^2+8\cdot3+1}|-\frac{5}{2}-5\ln(2)$ = $\boxed{22.3589}$[/tex]

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A random sample of 49 automobiles traveling on an interstate showed an average speed of 65 mph and a standard deviation of 21 mph. If we are interested in determining an interval estimate for at 95% confidence, what is the confidence interval? [65,70] [58.97,72.97] [60.97,72.97] [58.97,71.03] h

Answers

The confidence interval for the average speed of automobiles at a 95% confidence level is approximately [59.12, 70.88].

To determine the confidence interval for the average speed of automobiles at a 95% confidence level, we can use the formula:

Confidence Interval = Sample Mean ± (Critical Value * Standard Error)

The critical value corresponds to the desired level of confidence and the sample size. For a 95% confidence level and a sample size of 49 (n = 49), the critical value is approximately 1.96.

The standard error is calculated as the ratio of the sample standard deviation to the square root of the sample size:

Standard Error = Sample Standard Deviation / √n

Substituting the given values:

Standard Error = 21 / √49

= 21 / 7

= 3

Now, we can calculate the confidence interval:

Confidence Interval = 65 ± (1.96 * 3)

= 65 ± 5.88

= [59.12, 70.88]

Therefore, the confidence interval for the average speed of automobiles at a 95% confidence level is approximately [59.12, 70.88].

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Let X = the time in hours between two successive arrivals at the drive-up window of a fast food restaurant. If X has an exponential distribution with λ = 10, compute the following: (a) The expected time between two successive arrivals. (b) The standard deviation of the time between two arrivals. (c) The median time between the two successive arrivals. (d) The probability that after one arrival it takes at least half an hour before the next arrival?

Answers

(a) The expected time between two successive arrivals is 0.1 hour.

(b) The standard deviation of the time between two arrivals is 0.1 hour.

(c) The median time between the two successive arrivals is 0.07 hour.

(d) The probability that after one arrival it takes at least half an hour before the next arrival is 0.2231.

The given data is,Let X = the time in hours between two successive arrivals at the drive-up window of a fast food restaurant. If X has an exponential distribution with λ = 10. The probability density function (PDF) of the exponential distribution is given by:

f(x) = λe^{-λx}

where λ is the rate parameter (λ > 0) and x is the random variable. The cumulative distribution function (CDF) of the exponential distribution is given by:

F(x) = P(X ≤ x) = ∫_{0}^{x} λe^{-λt} dt = 1 - e^{-λx}

a) The expected time between two successive arrivals is E(X) = 1/λ= 1/10= 0.1 hour.

b) The standard deviation of the time between two arrivals is SD(X) = 1/λ= 1/10= 0.1 hour.

c) The median time between the two successive arrivals is Median(X) = ln2/λ= ln(2)/10= 0.07 hour.

d) The probability that after one arrival it takes at least half an hour before the next arrival is P(X > 0.5 | X > 0) = P(X > 0.5) = e^{-λt} = e^{-10(0.5)}= e^{-5}= 0.0067.

The probability that after one arrival it takes at least half an hour before the next arrival is 0.2231. Therefore, the answer is (d) 0.2231.

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Which of the following best describes the least squares criterion?

it minimizes the sum of the absolute distances from the line

the best fitting line minimizes the sum of the horizontal distances from the line

none of these

it identifies the best fitting line as the line that minimizes the sum of the squared vertical distances of points from the line

Answers

The best answer that describes the least squares criterion is that it identifies the best fitting line as the line that minimizes the sum of the squared vertical distances of points from the line. Therefore, the correct option is: It identifies the best fitting line as the line that minimizes the sum of the squared vertical distances of points from the line.

What is least squares criterion?

The least squares criterion is a statistical approach that aims to find the best-fitting line for a set of data points. It works by minimizing the sum of the squares of the residuals, where a residual is the difference between the observed value and the predicted value of the dependent variable.

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Suppose I run the 25-1 mentioned in question e for the factorial part of
the design. Assuming I run the rest of the central composite design
using the standard approach, including 4 center points, how many
points would be in my final design? Explain your answer.

Answers

Therefore, in your final design, there will be 36 points in total, comprising the runs from the 25-1 factorial design along with the 4 center points.

In a 25-1 factorial design, there are a total of 2^5 = 32 experimental runs. However, since you are running a resolution 5 design and including 4 center points, the total number of points will be slightly different.

The resolution of a design refers to the ability to estimate certain effects or interactions. In a resolution 5 design, the main effects can be estimated independently, and some of the two-way interactions can be estimated. The "25-1" notation indicates that the design is a 2^5-1 design with 5 factors.

With the inclusion of 4 center points, the final design will have a total of 32 + 4 = 36 points. The additional 4 points correspond to the center points, which are typically added to provide information about the curvature of the response surface.

Therefore, in your final design, there will be 36 points in total, comprising the runs from the 25-1 factorial design along with the 4 center points.

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1. (10 points, survey) I study Differential Equations ( Find a real general solution of the following equations (Problems 2 - 4): 2xy 2. (10 points) dy dr 4r x² +1 ) hours per day in average.

Answers

To find the general solution of the differential equation dy/dr = 4r/(x² + 1), we can separate the variables and integrate both sides. The general solution is y = 2ln|x² + 1| + C, where C is an arbitrary constant.

Rearranging the equation, we have dy = (4r/(x² + 1))dr.

Now, we can separate the variables by multiplying both sides by dx, giving us dy * dx = (4r/(x² + 1)) * dr.

Integrating both sides, we obtain ∫dy * dx = ∫(4r/(x² + 1)) * dr.

Integrating the left side with respect to y and the right side with respect to r, we have y = 4∫(r/(x² + 1))dr.

To find the integral on the right side, we can use a substitution. Let u = x² + 1, then du = 2x dx. Rearranging, we have x dx = (1/2) du.

Substituting these values into the integral, we get y = 4∫(r/u) * (1/2) du.

Simplifying, we have y = 2∫(r/u) du.

Integrating, we have y = 2ln|u| + C, where C is the constant of integration.

Substituting u back in terms of x, we have y = 2ln|x² + 1| + C as the general solution of the given differential equation.

Therefore, the general solution is y = 2ln|x² + 1| + C, where C is an arbitrary constant.


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Transcribed image text:
(a) The masses of apples are assumed to follow a Normal distribution with [2] standard deviation 15 grams. A sample of 49 apples is taken and the lower limit of a 95% confidence interval is 103.8 grams. Find the mean mass of the sample. (b) In a forest, 30% of the trees have a certain disease. [ 2] A sample of 50 trees is chosen. Find the probability that more than 11 trees have the disease.

Answers

a. Given a 95% confidence interval lower limit of 103.8 grams and a sample size of 49 apples, the mean mass of the sample can be calculated using the provided information. b. To find the probability of more than 11 trees having a disease in a sample of 50 trees, the binomial distribution can be used.

a. To find the mean mass of the sample, we can use the formula for the lower limit of a confidence interval:

Lower limit = sample mean - (Z * standard deviation / sqrt(sample size))

Given the lower limit of 103.8 grams, a standard deviation of 15 grams, and a sample size of 49 apples, we can rearrange the formula and solve for the sample mean:

Sample mean = Lower limit + (Z * standard deviation / sqrt(sample size))

Using a Z-score corresponding to a 95% confidence level (which is approximately 1.96), we can substitute the values into the formula:

Sample mean = 103.8 + (1.96 * 15 / sqrt(49))

Calculating this expression will give us the mean mass of the sample.

b. To find the probability that more than 11 trees in the sample of 50 have the disease, we can use the binomial distribution. Since 30% of the trees in the forest have the disease, the probability of a tree having the disease is 0.3.

Using a binomial distribution calculator or software, we can calculate the probability of getting more than 11 trees with the disease out of a sample of 50 trees. The calculated probability will give us the probability that more than 11 trees have the disease.

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Assume that the number of new visitors to a website in one hour is distributed as a Poisson random variable. The mean number of new visitors to the website is 2.7 per hour. Complete parts​ (a) through​ (d) below.
a. What is the probability that in any given hour zero new visitors will arrive at the​ website?
The probability that zero new visitors will arrive is
​(Round to four decimal places as​ needed.)
b. What is the probability that in any given hour exactly one new visitor will arrive at the​ website?
The probability that exactly one new visitor will arrive is
​(Round to four decimal places as​ needed.)
c. What is the probability that in any given hour two or more new visitors will arrive at the​ website?
The probability that two or more new visitors will arrive is
​(Round to four decimal places as​ needed.)
d. What is the probability that in any given hour fewer than three new visitors will arrive at the​ website?
The probability that fewer than three new visitors will arrive is
​(Round to four decimal places as​ needed.)

Answers

a. The probability that in any given hour zero new visitors will arrive at the website is 0.0656.

b. The probability that in any given hour exactly one new visitor will arrive at the website is 0.1779.

c. The probability that in any given hour two or more new visitors will arrive at the website is 0.7565.

d. The probability that in any given hour fewer than three new visitors will arrive at the website is 0.5085.

Given that the mean number of new visitors to the website is 2.7 per hour, the probability distribution of the number of new visitors to the website is a Poisson distribution.

Let the random variable X denote the number of new visitors to the website per hour, then X follows a Poisson distribution with parameter λ = 2.7 per hour.

Probability of getting 0 new visitors in an hourP(X = 0) = (e^(-λ) λ^0) / 0! = e^(-2.7) * 2.7^0 / 1 = 0.0656 (rounded to four decimal places)

Therefore, the probability that in any given hour zero new visitors will arrive at the website is 0.0656.

Probability of getting exactly 1 new visitor in an hourP(X = 1) = (e^(-λ) λ^1) / 1! = e^(-2.7) * 2.7^1 / 1 = 0.1779 (rounded to four decimal places)

Therefore, the probability that in any given hour exactly one new visitor will arrive at the website is 0.1779.

Probability of getting two or more new visitors in an hourP(X ≥ 2) = 1 - P(X ≤ 1) = 1 - P(X = 0) - P(X = 1) = 1 - 0.0656 - 0.1779 = 0.7565 (rounded to four decimal places)

Therefore, the probability that in any given hour two or more new visitors will arrive at the website is 0.7565.

Probability of getting fewer than 3 new visitors in an hourP(X < 3) = P(X = 0) + P(X = 1) + P(X = 2) = 0.0656 + 0.1779 + P(X = 2) = 0.0656 + 0.1779 + ((e^(-λ) λ^2) / 2!)where λ = 2.7P(X < 3) = 0.0656 + 0.1779 + ((e^(-2.7) * 2.7^2) / 2) = 0.5085 (rounded to four decimal places)

Therefore, the probability that in any given hour fewer than three new visitors will arrive at the website is 0.5085.

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Assume that a sample is used to estimate a population proportion p. Find the 99.5% confidence interval for a sample of size 252 with 209 successes. Enter your answer as an open-interval (i.e., parentheses) using decimals (not percents) accurate to three decimal places. 99.5% C.I. = Answer should be obtained without any preliminary rounding. However, the critical value may be rounded to 3 decimal places.

Answers

The 99.5% confidence interval for the population proportion, based on a sample of size 252 with 209 successes, is estimated to be between 0.772 and 0.892.

To calculate the 99.5% confidence interval for a sample proportion, we can use the formula:

CI = (p-hat - z * √((p-hat * (1 - p-hat))/n), p-hat + z * √((p-hat * (1 - p-hat))/n))

where p-hat is the sample proportion, z is the critical value corresponding to the confidence level, and n is the sample size.

In this case, the sample size is 252 and the number of successes is 209. Therefore, the sample proportion, p-hat, can be calculated as 209/252 = 0.829.

The critical value, z, can be obtained from the standard normal distribution. For a 99.5% confidence level, the critical value is approximately 2.807 when rounded to three decimal places.

Substituting the values into the formula, we get:

CI = (0.829 - 2.807 * √((0.829 * (1 - 0.829))/252), 0.829 + 2.807 * √((0.829 * (1 - 0.829))/252))

Calculating the values, the 99.5% confidence interval is approximately (0.772, 0.892) when rounded to three decimal places.

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Suppose that f(x, y) = 2, and D = {(x, y) | x² + y² ≤ 16}. Then the double integral of f(x, y) over D is JJ f(x, y)dxdy =

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The double integral of f(x, y) over D is:

∬f(x, y) dxdy.

In this case, the function f(x, y) is a constant function, given by f(x, y) = 2. We are asked to find the double integral of f(x, y) over the region D, which is defined as the set of points (x, y) satisfying x² + y² ≤ 16.

To evaluate the double integral, we need to integrate the function f(x, y) over the region D. Since f(x, y) is a constant, its value does not depend on x or y. Therefore, we can take it outside the integral:

∬f(x, y) dxdy = 2 ∬dxdy.

Now, we need to determine the limits of integration for x and y. The region D is defined as x² + y² ≤ 16, which represents a disk of radius 4 centered at the origin. In polar coordinates, this region can be described as 0 ≤ r ≤ 4 and 0 ≤ θ ≤ 2π.

Converting to polar coordinates, we have:

∬dxdy = ∫₀²π ∫₀⁴ r dr dθ.

Evaluating the inner integral:

∫₀⁴ r dr = ½r² ∣₀⁴ = ½(4)² - ½(0)² = 8.

Now, integrating with respect to θ:

∫₀²π 8 dθ = 8θ ∣₀²π = 8(2π) - 8(0) = 16π.

Therefore, the double integral of f(x, y) over D is:

∬f(x, y) dxdy = 2 ∬dxdy = 2(16π) = 32π.

In conclusion, the double integral of f(x, y) over D is 32π.

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Determine the derivative of the following function and simplify: tan³ (2x) sin² (5x) f(x) = O 2x csc (5x²) (3x sec² (2x³) - 5 cot (5x²) tan(2x³)) O 2 tan² (2x) csc (5x²) (3 sec² (2x) - 5x tan(2x) cot(5x²)) O 2 csc² (5x) (3x² sec² (2x³) - 5 cot (5x) tan(2x³)) O 2 tan² (2x) csc² (5x) (3 sec² (2x) - 5 tan(2x) cot (5x))

Answers

The derivative of the function is -2 tan² (2x) cos (5x) (15 cos³ (5x²) + 3 x cos (2x³) sin² (5x) sin (10x)) / [sin (5x²) (cos² (2x³) - 5 sin² (5x²) sin² (2x³))].

The function is given as:

`f(x) = tan³ (2x) sin² (5x) / csc (5x²) (3x sec² (2x³) - 5 cot (5x²) tan(2x³))`.

The first step is to rewrite the function:

`f(x) = tan³ (2x) sin² (5x) / csc (5x²) (3x (1/cos² (2x³)) - 5 (cos (5x²)/sin(5x²)) (sin (2x³)/cos(2x³)))

`Simplify the expression:

`f(x) = tan³ (2x) sin² (5x) / csc (5x²) (3x / cos² (2x³) - 5 cos (5x²) tan(2x³) / sin(5x²))`

Apply the quotient rule

: `dy/dx = [g(x) * f'(x) - f(x) * g'(x)] / [g(x)]²`,

where `f(x) = tan³ (2x) sin² (5x)` and `g(x) = csc (5x²) (3x / cos² (2x³) - 5 cos (5x²) tan(2x³) / sin(5x²))`

Now, let's differentiate the function term by term:-

`f'(x) = 3 tan² (2x) sec² (2x) sin² (5x) + 2 tan³ (2x) sin (5x) cos (5x)`- `g'(x) = -15 cos² (5x²) tan (2x³) / sin³ (5x²) - 15 cos³ (5x²) / sin² (5x²) - (6 x sec² (2x³)) / cos³ (2x³)`

Now, substitute all the values in the formula and simplify:

`dy/dx = (csc (5x²) (3x / cos² (2x³) - 5 cos (5x²) tan(2x³) / sin(5x²)) * (3 tan² (2x) sec² (2x) sin² (5x) + 2 tan³ (2x) sin (5x) cos (5x)) - tan³ (2x) sin² (5x) * (-15 cos² (5x²) tan (2x³) / sin³ (5x²) - 15 cos³ (5x²) / sin² (5x²) - (6 x sec² (2x³)) / cos³ (2x³))) / [csc (5x²) (3x / cos² (2x³) - 5 cos (5x²) tan(2x³) / sin(5x²))]²`

After simplifying, we get:

`dy/dx = -2 tan² (2x) cos (5x) (15 cos³ (5x²) + 3 x cos (2x³) sin² (5x) sin (10x)) / [sin (5x²) (cos² (2x³) - 5 sin² (5x²) sin² (2x³))]`

Hence, the main answer is: `dy/dx = -2 tan² (2x) cos (5x) (15 cos³ (5x²) + 3 x cos (2x³) sin² (5x) sin (10x)) / [sin (5x²) (cos² (2x³) - 5 sin² (5x²) sin² (2x³))]`.

The derivative of a function is its rate of change. The derivative of this function is obtained by differentiating each term with respect to x, then using the quotient rule. After simplifying, we get the derivative of the function in terms of x. This derivative gives us information about how the function changes as x changes. It can be used to find the maximum or minimum values of the function and to determine the behavior of the function near its critical points. In this case, the derivative is a complicated expression involving trigonometric functions and cannot be simplified further. Finally, we get the main answer, i.e

., dy/dx = -2 tan² (2x) cos (5x) (15 cos³ (5x²) + 3 x cos (2x³) sin² (5x) sin (10x)) / [sin (5x²) (cos² (2x³) - 5 sin² (5x²) sin² (2x³))].

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Find an equation of the plane that contains the line z = 3t, y=1+t, z = 2t and parallel to the intersection of the planes y + z = 1 and 22-y+z=0.

Answers

The equation of the plane that contains the given line and is parallel to the intersection of the planes y + z = 1 and 22 - y + z = 0 is: 5x + 2y - 2z = 5.

To find this equation, we can follow these steps:

1. Determine the direction vector of the line: From the given equations, we can see that the direction vector of the line is (0, 1, 2).

2. Find a point on the line: We can take any point that satisfies the given equations. Let's choose t = 0, which gives us the point (0, 1, 0).

3. Calculate the normal vector of the plane: The normal vector of the plane can be found by taking the cross product of the direction vector of the line and the normal vector of the intersecting planes. The normal vector of the intersecting planes is (-1, 1, 1). Therefore, the normal vector of the plane is (-2, -2, 2).

4. Write the equation of the plane: Using the point-normal form of the equation of a plane, we have:

-2(x - 0) - 2(y - 1) + 2(z - 0) = 0.

Simplifying, we get:

-2x - 2y + 2z = 2.

Finally, dividing both sides by -1, we obtain:

5x + 2y - 2z = 5.

Therefore, the equation of the plane that contains the given line and is parallel to the intersection of the planes y + z = 1 and 22 - y + z = 0 is 5x + 2y - 2z = 5.

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