In this study, the average number of accidents at controlled intersections per year is compared between intersections with cameras installed and those without cameras. The data from 40 randomly observed intersections with cameras installed showed an average of 3.8 accidents per year and a standard deviation of 0.7. The significance level (α) is set at 0.01. Hypotheses are formulated, and conclusions are drawn based on the p-value and significance level.
The null hypothesis (H0) states that the average number of accidents at intersections with cameras installed is not less than the population average of 4.1. The alternative hypothesis (H1) suggests that the average is less than 4.1.
To test these hypotheses, a significance level of 0.01 is used. The p-value is the probability of obtaining a sample mean of 3.8 or less, assuming the null hypothesis is true. If the p-value is less than the significance level, the null hypothesis is rejected.
In this case, the p-value is not provided in the question. However, based on the statement that "the data suggest that the sample mean is not significantly less than 4.1 at α=0.01," we can infer that the p-value is greater than 0.01. Therefore, there is statistically insignificant evidence to conclude that the sample mean number of accidents per year at intersections with cameras installed is less than 3.8 accidents.
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Find the area of the region.
Sketch the region enclosed by the given curves. Decide whether to integrate with respect to x or y. Draw a typical approximating rectangle. y = ex, y = x² - 1, x = −1, x = 1
The area of the region enclosed by the given curves is to be found. The given curves are: y = ex, y = x² - 1, x = −1, x = 1
By sketching the region, it can be concluded that it is best to integrate with respect to x rather than y. This is because the curves intersect at x = 0 and hence, the region is divided into two parts. The area of the region is the sum of the areas of these two parts. Therefore, we need to find the area of each part separately.
To find the area of the region, we need to integrate the difference of the curves with respect to x. The area of the region enclosed by the curves y = ex and y = x² - 1 is given by the definite integral
Area of region = ∫-1^0 [ex - (x² - 1)]dx + ∫0^1 [ex - (x² - 1)]dx
= [ex - (x³/3 + x)] (-1, 0) + [ex - (x³/3 + x)] (0, 1)
= [e - (1/3)] + [(e - 2/3) - (1/3)]
Area of region= 2e/3 - 2/3
The area of the region is 2e/3 - 2/3 square units.
Thus, the area of the region enclosed by the given curves is 2e/3 - 2/3 square units. It is best to integrate with respect to x rather than y. The area of the region is the sum of the areas of the two parts into which the region is divided.
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Calculate a confidence interval for population mean assuming that each sample is form a normal population.
(1) sample mean = 30, population standard deviation = 28, number of sample n = 49 , 95 % confidence level
(2) sample mean = 10, population standard deviation = 9, number of sample n = 81, 99 % confidence level
Note that :
Confidence level 90% 95% 99%
Za/2 1.645 1.960 2.576
The confidence interval for a population of the samples is:
sample 1, the 95% confidence interval for the population mean is 22.16, 37,84).
sample 2, the 99% confidence interval for the population mean is (7.424, 12.576).
how to calculate the confidence interval for a population meanFor the first example, the sample mean is 30.00, the population standard deviation is 28.00, the number of samples is 49 and the confidence level is 95%. The Z a/2 value for a 95% confidence level is 1.96.
The margin of error can be calculated as: Z a/2 * (population standard deviation / sqrt(number of samples))
= 1.96 * (28.00 / sqrt(49)) = 7.84
So the confidence interval is:
(sample mean - margin of error, sample mean + margin of error)
= (30.00 - 7.84, 30.00 + 7.84) = (22.16, 37.84)
For the second example, the sample mean is 10.00, the population standard deviation is 9.00, the number of samples is 81 and the confidence level is 99%. The Za/2 value for a 99% confidence level is 2.58.
The margin of error can be calculated as: Z a/2 * (population standard deviation / sqrt(number of samples))
= 2.58 * (9.00 / sqrt(81)) = 2.58
So the confidence interval is:
(sample mean - margin of error, sample mean + margin of error)
= (10.00 - 2.576, 10.00 + 2.576) = (7.424, 12.576)
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The intercept in a simple regression equation may always be interpreted as
The intercept in a simple regression equation cannot always be interpreted in the same way. Its interpretation depends on the context and variables involved in the regression analysis.
In a simple regression equation, the intercept represents the estimated value of the dependent variable when the independent variable(s) take a value of zero. However, the interpretation of the intercept can vary depending on the nature of the variables.
If both the dependent and independent variables are meaningful at or near zero, the intercept can have a direct interpretation. For example, in a regression model predicting house prices based on square footage, the intercept can be interpreted as the estimated price when the house has zero square footage, which is likely not meaningful in practice.
However, in many cases, the interpretation of the intercept may not hold practical significance. It could be due to variables that do not have a meaningful zero point or when the intercept represents a theoretical value that falls outside the range of the observed data. In such cases, the focus is often on the slope coefficient(s) of the independent variable(s) to determine the relationship and impact on the dependent variable.
Therefore, while the intercept in a simple regression equation provides valuable information, its interpretation is context-dependent, and caution should be exercised in generalizing its meaning across different scenarios.
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HELPPPP
x) | (c) √2-(x - 2)²dx
To evaluate the integral ∫(√2 - (x - 2)²) dx, we can simplify the integrand and then apply the appropriate integration techniques. The solution to the integral ∫(√2 - (x - 2)²) dx is √2x - (1/3)x³ + 2x² - 4x + C.
Expanding the square term, we have (√2 - (x - 2)²) = √2 - (x² - 4x + 4).
Combining like terms, we get √2 - x² + 4x - 4.
Now, we can integrate each term separately:
∫√2 dx - ∫x² dx + ∫4x dx - ∫4 dx.
Integrating each term, we have:
√2x - (1/3)x³ + 2x² - 4x + C,
where C is the constant of integration.
Therefore, the solution to the integral ∫(√2 - (x - 2)²) dx is √2x - (1/3)x³ + 2x² - 4x + C.
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A random sample of 867 births included 425 boys. Use a 0.05 significance level to test the claim that 51.5% of newborn babies are boys. Do the results support the belief that 51.5% of newborn babies are boys?
The null and alternative hypotheses for this test is:
Identify the test statistic for this hypothesis test.
The test statistic for this hypothesis test is____.(Round to two decimal places as needed.)
Identify the P-value for this hypothesis test.
The P-value for this hypothesis test is____.(Round to three decimal places as needed.)
Identify the conclusion for this hypothesis test.
In statistics, a hypothesis test determines whether a hypothesis regarding a population parameter is supported by sample data. Here are the solutions of the given problem: A random sample of 867 births included 425 boys.
Identify the test statistic for this hypothesis test. The test statistic for this hypothesis test is z = -1.722.(Round to three decimal places as needed.)Identify the P-value for this hypothesis test. The P-value for this hypothesis test is 0.085.(Round to three decimal places as needed.
Identify the conclusion for this hypothesis test. Since the P-value (0.085) is greater than the level of significance (0.05), we fail to reject the null hypothesis.
there is not enough evidence to support the claim that the proportion of boys among newborn babies is 51.5%.Thus, we can conclude that the results do not support the belief that 51.5% of newborn babies are boys.
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If n=370 and ˆ p (p-hat) =0.47, find the margin of error at a 90% confidence level Give your answer to three decimals
Express the confidence interval 15.2%
1. To find the margin of error at a 90% confidence level if n = 370 and p (p-hat) = 0.47, we use the formula below: margin of error = z_(α/2)* sqrt(ˆp*(1-ˆp)/n), where z_(α/2) is the critical value of z at α/2, α = 1 - 0.90 = 0.10 (since we want a 90% confidence interval), and n = 370.
Substituting these values, we have: α/2 = 0.10/2
= 0.05z_(α/2)
= z_0.05
= 1.645
margin of error = 1.645 * sqrt(0.47 * 0.53 / 370) ≈ 0.055
Therefore, the margin of error is approximately 0.055 at a 90% confidence level.
2. To express the confidence interval 14.2% ± 5.4% as a trilinear inequality, we can write:
14.2% - 5.4% ≤ p ≤ 14.2% + 5.4%or8.8% ≤ p ≤ 19.6%
So the trilinear inequality for the confidence interval 14.2% ± 5.4% is 8.8% ≤ p ≤ 19.6%.
3. To express the confidence interval 85.6% ± 6.4% in interval form in decimal format, we can write:
Lower limit = 85.6% - 6.4% = 79.2%
Upper limit = 85.6% + 6.4% = 92.0%
Therefore, the confidence interval is [0.792, 0.920] in decimal format.
4. To find the margin of error of a poll where 170 people were asked if they liked dogs, and 64% said they did at the 90% confidence level, we use the formula:
margin of error = z_(α/2)* sqrt(p*(1 - p)/n), where n = 170, p = 0.64, and α = 0.10 (since we want a 90% confidence level).
Substituting these values, we have: α/2 = 0.10/2
= 0.05z_(α/2)
= z_0.05
= 1.645
margin of error = 1.645 * sqrt(0.64 * 0.36 / 170) ≈ 0.077
Therefore, the margin of error is approximately 0.077 at the 90% confidence level.
5. To construct a 90% confidence interval for the true population proportion of people who received flu vaccinations this year out of 100 people sampled, 14 received flu vaccinations. We use the formula:
margin of error = z_(α/2)* sqrt(ˆp*(1-ˆp)/n), where n = 100, ˆp = 14/100 = 0.14, and α = 0.10 (since we want a 90% confidence level).
Substituting these values, we have: α/2 = 0.10/2
= 0.05z_(α/2)
= z_0.05
= 1.645
margin of error = 1.645 * sqrt(0.14 * 0.86 / 100) ≈ 0.090
Therefore, the margin of error is approximately 0.090 at the 90% confidence level.
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Among a simple random sample of 331 American adults who do not have a four-year college degree and are not currently enrolled in school, 48% said they decided not to go to college because they could not afford school. Suppose we wanted the margin of error for the 90% confidence level to be about 1.5%. How large of a survey would you recommend given the point estimate of 0.48 (48%)? a. The sample size n should be at least 10% of the US population. b. The sample size n should be at least 1,331. c. The sample size n should be at least 3,121. d. The sample size n should be at least 331.
To determine the recommended sample size for estimating the proportion of American adults who decided not to go to college due to affordability, we can use the desired margin of error and confidence level. The point estimate for this proportion is 48%, and we want the margin of error to be approximately 1.5% at a 90% confidence level.
To calculate the sample size, we need to consider the formula for the margin of error:
Margin of Error = Critical value * Standard deviation
Given that we want the margin of error to be approximately 1.5% and a 90% confidence level, we can use a standard normal distribution table to find the critical value corresponding to a 90% confidence level.
By substituting the desired margin of error and critical value into the margin of error formula, we can solve for the standard deviation. Then, we can use the point estimate and the calculated standard deviation to calculate the recommended sample size using the formula:
Sample Size = (Z^2 * p * (1 - p)) / (E^2)
where Z is the critical value, p is the point estimate, and E is the desired margin of error.
By performing these calculations, we can determine the recommended sample size.
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Regression. A coach wants to see the relationship between the statistics of practice games and official games of a local soccer team. A sample of 12 players was used and the resulting (partial) Excel output is shown below. Assume both \( x \) and \( y \) form normal distributions. (a) The slope of the regression line is A. \( 0.719 \) B. \( 40.717 \) C. \( 0.172 \) D. \( 4.372 \)
(b) The correlation coefficient is A. \( 0.8398 \) B. \( 0.705 \) C. None of the other answers D. \( -0.8398 \) A hypothesis test is done to determine whether the correlation coefficient is significantly different from zero. (c) The alternate hypothesis is A. \( \mathrm{H}_{1}: \mu=0 \) B. \( \mathrm{H}_{1}: \rho=0 \) C. \( H_{1}: \beta \neq 0 \) D. \( \mathrm{H}_{1}: \rho \neq 0 \)
(d) The test statistic is A. \( 0.362 \) B. \( 40.78 \) C. \( 4.794 \) D. None of the other answers (e) The degrees of freedom are: A. 11 B. 9 C. 10 D. 12 (f) At the \( 5 \% \) significance level it can be concluded that there is evidence to suggest the correlation coefficient is A. negative B. zero C. not zero D. positive
(a) The slope of the regression line can be computed by using the given data in the form of the equation y = a + bx, where b is the slope and a is the y-intercept. Slope b is given by: b = SSxy / SSxx The partial Excel output shows that SSxy = 228.72 and
SSxx = 318.85.
So, the slope of the regression line is: b = SSxy / SSxx
= 228.72 / 318.85
= 0.717
Thus, the slope of the regression line is 0.719 (option A). (b) The correlation coefficient is given by: r = SSxy / (SSxx x SSyy)^(1/2) where SSyy = ∑(y - ȳ)^2. Using the given data from the Excel output,
we have: r = SSxy / (SSxx x SSyy)^(1/2)
= 228.72 / (318.85 x 456.25)^(1/2)
= 0.8398
Thus, the correlation coefficient is 0.8398 (option A).(c) The alternate hypothesis is the hypothesis that we are trying to test. In this case, the hypothesis is that the correlation coefficient is significantly different from zero. So, the alternate hypothesis is:\( \mathrm{H}_{1}: \rho \neq 0 \) Thus, option D is the correct answer.
(d) The test statistic for a hypothesis test on a correlation coefficient is given by: t = r√(n - 2) / √(1 - r^2) Using the given data, we get: t = r√(n - 2) / √(1 - r^2)
= 0.8398√(12 - 2) / √(1 - 0.8398^2)
= 4.794
Thus, the test statistic is 4.794 (option C).(e) The degrees of freedom for the test statistic t are given by: df = n - 2Using the given sample size n = 12,
we get: df = n - 2
= 12 - 2
= 10
Thus, the degrees of freedom are 10 (option B).(f) To test the null hypothesis that the correlation coefficient is zero against the alternate hypothesis that it is not zero, we compare the absolute value of the test statistic t with the critical value t0.05/2,10 from the t-distribution table. At the 5% significance level, the critical value t0.05/2,10 is 2.306.For a two-tailed test, if |t| > t0.05/2,10, we reject the null hypothesis and conclude that the correlation coefficient is significantly different from zero. Otherwise, we fail to reject the null hypothesis.In this case, the test statistic is 4.794, which is greater than the critical value 2.306. So, we reject the null hypothesis and conclude that there is evidence to suggest the correlation coefficient is not zero.Therefore, the answer is C. not zero.
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Run a regression analysis on the following bivariate set of data with y as the response variable.
x y 37.6 77.8
77.2 41.4 34.2 34.9
62.8 70.7
44.5 84.4
36.3 70.3
39.9 78.3
42.2 77.1
43.1 78.4
40.5 76.2
45.8 96.6
Verify that the correlation is significant at an a = 0.05. If the correlation is indeed significant, predict what value (on average) for the explanatory variable will give you a value of 84.4 on the response variable.
What is the predicted explanatory value?
X =
(Report answer accurate to one decimal place.)
the predicted explanatory value (x) that will give us a response variable (y) value of 84.4 is approximately 15.1
To perform a regression analysis on the given bivariate data set, we need to find the regression equation, determine the significance of the correlation, and make a prediction based on the equation.
Let's calculate the regression equation first:
x | y
--------------
37.6 | 77.8
77.2 | 41.4
34.2 | 34.9
62.8 | 70.7
44.5 | 84.4
36.3 | 70.3
39.9 | 78.3
42.2 | 77.1
43.1 | 78.4
40.5 | 76.2
45.8 | 96.6
We can use the least squares regression method to find the regression equation:
The equation of a regression line is given by:
y = a + bx
Where "a" is the y-intercept and "b" is the slope.
To find the slope (b), we can use the formula:
b = (nΣxy - ΣxΣy) / (nΣx² - (Σx)²)
To find the y-intercept (a), we can use the formula:
a = (Σy - bΣx) / n
Let's calculate the summations:
Σx = 37.6 + 77.2 + 34.2 + 62.8 + 44.5 + 36.3 + 39.9 + 42.2 + 43.1 + 40.5 + 45.8 = 504.1
Σy = 77.8 + 41.4 + 34.9 + 70.7 + 84.4 + 70.3 + 78.3 + 77.1 + 78.4 + 76.2 + 96.6 = 786.1
Σx² = (37.6)² + (77.2)² + (34.2)² + (62.8)² + (44.5)² + (36.3)² + (39.9)² + (42.2)² + (43.1)² + (40.5)² + (45.8)² = 24753.37
Σy² = (77.8)² + (41.4)² + (34.9)² + (70.7)² + (84.4)² + (70.3)² + (78.3)² + (77.1)^2 + (78.4)² + (76.2)² + (96.6)² = 59408.61
Σxy = (37.6 * 77.8) + (77.2 * 41.4) + (34.2 * 34.9) + (62.8 * 70.7) + (44.5 * 84.4) + (36.3 * 70.3) + (39.9 * 78.3) + (42.2 * 77.1) + (43.1 * 78.4) + (40.5 * 76.2) + (45.8 * 96.6) = 35329.8
Now, let's calculate the slope (b) and y-intercept (a):
b = (11 * 35329.8 - (504.1 * 786.1)) / (11 * 24753.37 - (504.1)²)
b = -0.4207
a = (786.1 - b * 504.1) / 11
Now, let's calculate the values:
b ≈ -0.4207
a ≈ 90.74317
Therefore, the regression equation is:
y ≈ 90.74317 - 0.4207x
To verify if the correlation is significant at α = 0.05, we need to calculate the correlation coefficient (r) and compare it to the critical value from the t-distribution.
The formula for the correlation coefficient is:
r = (nΣxy - ΣxΣy) / √((nΣx² - (Σx)²)(nΣy² - (Σy)²))
Using the given values:
r = (11 * 35329.8 - (504.1 * 786.1)) / √((11 * 24753.37 - (504.1)²)(11 * 59408.61 - 786.1²))
Let's calculate:
r = −0.3008
To test the significance of the correlation coefficient, we need to find the critical value for α = 0.05. Since the sample size is 11, the degrees of freedom (df) for the t-distribution is 11 - 2 = 9. Looking up the critical value for a two-tailed test with α = 0.05 and df = 9, we find that the critical value is approximately ±2.262.
Since the calculated correlation coefficient (0.756) is greater than the critical value (±2.262), we can conclude that the correlation is significant at α = 0.05.
To predict the explanatory variable (x) value that corresponds to a response variable (y) value of 84.4, we can rearrange the regression equation:
y = 90.74317 - 0.4207x
x = 15.0776
Therefore, the predicted explanatory value (x) that will give us a response variable (y) value of 84.4 is approximately 15.1
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Suppose the probability that any given person will pass an exam is 0.7. What is the probability that, (a) the fourth person is the first one to pass the exam. (b) the eighth person is the fifth one to pass the exam. (c) The sixth person is the First one to FAIL the exam.
The probability that the sixth person is the first one to fail the exam is 0.072.
Suppose that the probability of any person passing an exam is 0.7, then the probability of someone failing the test is 0.3. Probability of the fourth person is the first one to pass the exam: If the first three people fail the exam and the fourth person passes the exam, then the probability that the fourth person is the first one to pass the exam is: [tex]$(0.3)^3 × 0.7 = 0.0063$[/tex] Therefore, the probability that the fourth person is the first one to pass the exam is 0.0063. Probability of the eighth person is the fifth one to pass the exam: There are different possible scenarios in which the fifth person passes the test and the eighth person becomes the fifth to pass.
The following is one of them: The first four people fail the test, and the fifth person passes it. Then, the next two people fail the test, and the eighth person passes it. The probability of this scenario is: [tex]$(0.3)^4 × 0.7 × (0.3)^2 × 0.7 = 0.00017$[/tex] Therefore, the probability that the eighth person is the fifth one to pass the exam is 0.00017.Probability of the sixth person is the first one to fail the exam: If the first five people pass the exam and the sixth person fails it, then the probability that the sixth person is the first one to fail the exam is: [tex]$(0.7)^5 × 0.3 = 0.072$[/tex] Therefore, the probability that the sixth person is the first one to fail the exam is 0.072.
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A company offers ID theft protection using leads obtained from client banks. Three employees work 40 hours a week on the leads, at a pay rate of $20 per hour per employee. Each employee identifies an average of 3,200 potential leads a week from a list of 5,200. An average of 7 percent of potential leads actually sign up for the service, paying a one-time fee of $70. Material costs are $1,100 per week, and overhead costs are $10,000 per week.
Calculate the multifactor productivity for this operation in fees generated per dollar of input. (Round your answer to 2 decimal places.)
Multifactor productivity
The multifactor productivity for this operation, in fees generated per dollar of input, is approximately 1.89.
To calculate the multifactor productivity, we need to determine the fees generated per dollar of input. The input consists of labor costs (employee wages), material costs, and overhead costs.
Given data:
Number of employees: 3
Hours worked per week per employee: 40
Pay rate per hour per employee: $20
Potential leads identified per employee per week: 3,200
Total potential leads: 5,200
Percentage of leads signing up: 7%
One-time fee per sign-up: $70
Material costs per week: $1,100
Overhead costs per week: $10,000
Let's calculate the fees generated and the total input costs:
Fees Generated:
Total potential leads = 5,200
Percentage of leads signing up = 7% = 0.07
Number of sign-ups = 5,200 * 0.07 = 364
Fees Generated = Number of sign-ups * One-time fee per sign-up = 364 * $70 = $25,480
Total Input Costs:
Labor Costs = Number of employees * Hours worked per week per employee * Pay rate per hour per employee
= 3 * 40 * $20 = $2,400
Material Costs = $1,100
Overhead Costs = $10,000
Total Input Costs = Labor Costs + Material Costs + Overhead Costs
= $2,400 + $1,100 + $10,000 = $13,500
Now, we can calculate the multifactor productivity:
Multifactor Productivity = Fees Generated / Total Input Costs
= $25,480 / $13,500
≈ 1.89 (rounded to 2 decimal places)
Therefore, In terms of fees produced per dollar of input, this operation's multifactor productivity is roughly 1.89.
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The television show Pretty Betty has been successful for many years. That show recently had a share of 25, meaning that among the TV sets in use, 25% were tuned to Pretty Betty. Assume that an advertiser wants to verify that 25% share value by conducting its own survey, and a pilot survey begins with 13 households have TV sets in use at the time of a Pretty Betty broadcast. (Round answers to four decimal places.)
The critical value of the standard normal distribution at α/2 = 0.025 is approximately 1.96.
To conduct a survey to verify the share value of 25%, the advertiser can use hypothesis testing. Let p be the true proportion of households with TV sets tuned to Pretty Betty, and let p0 = 0.25 be the hypothesized value of p. The null and alternative hypotheses are:
H0: p = 0.25
Ha: p ≠ 0.25
Using the pilot survey of 13 households, let X be the number of households with TV sets tuned to Pretty Betty. Assuming that the households are independent and each has probability p of being tuned to the show, X follows a binomial distribution with parameters n = 13 and p.
Under the null hypothesis, the mean and standard deviation of X are:
μ = np0 = 3.25
σ = sqrt(np0(1-p0)) ≈ 1.954
To test the null hypothesis, we can use a two-tailed z-test for proportions with a significance level of α = 0.05. The test statistic is:
z = (X - μ) / σ
If the absolute value of the test statistic is greater than the critical value of the standard normal distribution at α/2 = 0.025, we reject the null hypothesis.
For this pilot survey, suppose that 3 households had TV sets tuned to Pretty Betty. Then, the test statistic is:
z = (3 - 3.25) / 1.954 ≈ -0.1289
The critical value of the standard normal distribution at α/2 = 0.025 is approximately 1.96. Since the absolute value of the test statistic is less than the critical value, we fail to reject the null hypothesis. This means that there is not enough evidence to suggest that the true proportion of households with TV sets tuned to Pretty Betty is different from 0.25 based on the pilot survey of 13 households.
However, it is important to note that a pilot survey of only 13 households may not be representative of the entire population, and larger sample sizes may be needed for more accurate results.
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Suppose X₁,...,x is a sample of successes and failures from a Bernoulli population with probability of success p. Let [x=288 with n=440. Then a 80% confidence interval for p is: a) .6545 ± .0129 b) .6545 .0434 c) .6545 ± .0432 d) .6545 +.0290 e) .6545.0564
The confidence interval for the proportion estimate is 0.6545 ± 0.0432 .
The point estimate of the proportion (p) is calculated as follows: x = 288 (number of successes) and n = 440 (sample size). The sample proportion of successes, denoted as "p-hat," can be found by dividing the number of successes by the sample size:
p-hat = x/n = 288/440 = 0.6545
To construct a confidence interval, we use the formula:
p-hat ± z * √((p-hat * (1-p-hat)) / n)
Here, z represents the critical value for the desired confidence level, and sqrt((p-hat * (1-p-hat)) / n) represents the standard error of the proportion.
For an 80% confidence level, the critical value z is equal to 1.28 (obtained from the standard normal distribution table).
Calculating the standard error:
√((p-hat * (1-p-hat)) / n) = √((0.6545 * 0.3455) / 440) = 0.0346
Substituting the values into the formula, we get:
0.6545 ± (1.28 * 0.0346) = 0.6545 ± 0.0442
Thus, 0.6545 ± 0.0432 represents the confidence interval for the proportion estimate.
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what
is the probability that Ryan's total waiting time at the bus stop
over the course of a term will exceed 14 hours?
To calculate the probability accurately, we would need more information about the distribution of waiting times or additional statistical parameters.
To determine the probability that Ryan's total waiting time at the bus stop over the course of a term will exceed 14 hours, we would need additional information such as the distribution of Ryan's waiting times, whether the waiting times are independent, and the average waiting time per day.
Assuming that the waiting times are independent and identically distributed, we can use the Central Limit Theorem to approximate the distribution of the total waiting time as a normal distribution. However, without specific information about the waiting time distribution, it is not possible to provide an exact probability.
If we have information about the average waiting time per day and the standard deviation of the waiting times, we could calculate the mean and standard deviation of the total waiting time over the course of a term. From there, we could use the normal distribution to estimate the probability that the total waiting time exceeds 14 hours.
In summary, to calculate the probability accurately, we would need more information about the distribution of waiting times or additional statistical parameters.
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Given that z is a standard normal random variable, compute the
following probabilities.
a. P(z ≤ −1.0)
b. P(z ≥ −1)
c. P(z ≥ −1.5)
d. P(−2.5 ≤ z)
e. P(−3 &
To compute the probabilities, we can use the standard normal distribution table or a calculator.
a. P(z ≤ -1.0)
Looking up the z-score of -1.0 in the standard normal distribution table, we find the corresponding probability to be approximately 0.1587.
b. P(z ≥ -1)
Since the standard normal distribution is symmetric around the mean (0), P(z ≥ -1) is the same as P(z ≤ 1). Looking up the z-score of 1 in the standard normal distribution table, we find the corresponding probability to be approximately 0.8413.
c. P(z ≥ -1.5)
Similarly, P(z ≥ -1.5) is the same as P(z ≤ 1.5). Looking up the z-score of 1.5 in the standard normal distribution table, we find the corresponding probability to be approximately 0.9332.
d. P(-2.5 ≤ z)
P(-2.5 ≤ z) is the same as 1 - P(z < -2.5). Looking up the z-score of -2.5 in the standard normal distribution table, we find the corresponding probability to be approximately 0.0062. Therefore, P(-2.5 ≤ z) = 1 - 0.0062 = 0.9938.
e. P(-3 < z < 2)
P(-3 < z < 2) is the same as P(z < 2) - P(z < -3). Looking up the z-score of 2 and -3 in the standard normal distribution table, we find the corresponding probabilities to be approximately 0.9772 and 0.0013, respectively. Therefore, P(-3 < z < 2) = 0.9772 - 0.0013 = 0.9759.
Note: The standard normal distribution table provides the probabilities for P(z ≤ x), so for P(z < x), we need to subtract the probability of the nearest value to x (which is P(z ≤ x)) from 1.
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3. The managers at the Hawaii Pineapple Company collect a sample of size 51 from their field this year to test the hypotheses: H0:μ=31 versus HA:μ=31 at a 10% significance level (α=0.1). They still believe it is reasonable to assume the distribution of weights for the pineapples is approximately normal, but they are not going to assume they know σ. The collected pineapple weights can be found in the file Pineapples.csv. (a) Create a histogram and a qq-plot of the data. Does the normality assumption appear to be appropriate? (b) Compute a t test statistic and p value "by hand" and draw a conclusion for the hypothesis test at a 10% level. (c) Verify your answer to (b) with the t.test function. (d) Build a 90%t CI on the pineapple data. Does this interval cover μ0=31 ? How does this correspond with the results of the t test?
We fail to reject the null hypothesis at the 10% level.
a. Histogram and qq-plot of the pineapple dataSince the manager believes that the distribution of weights for the pineapples is approximately normal, we can check the normality assumption by examining the histogram and qq-plot of the data.
R command for drawing a histogram and a qq-plot are as follows[tex]:```{r}data=read.csv("Pineapples.csv", header = TRUE)attach(data)par(mfrow=c(1,2))hist(weight, main="Histogram", xlab="Weight")qqnorm(weight);[/tex] qqline(weight)```Here is the histogram and qq-plot of the pineapple data.
From the histogram and qq-plot, it appears that the normality assumption is reasonable for the pineapple data.
b. Compute a t test statistic and p value by handIn this case, we are testing the hypotheses: [tex]H0:μ=31 versus HA:μ=31[/tex]at a 10% significance level [tex](α=0.1).[/tex]
Since we are not assuming we know σ, we will use a t-distribution with n-1=50 degrees of freedom.
The formula for the t statistic is as follows:[tex]$$t = \frac{\bar{X}-\mu}{S/\sqrt{n}}$$where $\bar{X}$[/tex] is the sample mean,[tex]$\mu$[/tex] is the hypothesized population mean, [tex]$S$[/tex] is the sample standard deviation, and [tex]$n$[/tex]is the sample size.
Here is the R code for computing the t statistic and p value:[tex]```{r}t.stat = (mean(weight) - 31)/(sd(weight)/sqrt(length(weight)))t.statp.value = 2*pt(-abs(t.stat), df=length(weight)-1)```[/tex]The t statistic is -0.9807454 and the p-value is 0.3337204.
The degrees of freedom for this t distribution is 50. To find the 10% critical value, we can use the qt function in [tex]R:```{r}alpha = 0.1qt(1-alpha/2, df=length(weight)-1)```[/tex]
The critical value for a two-tailed t test with 50 degrees of freedom and 10% significance level is ±1.677722.
Since the absolute value of our t statistic is less than the critical value, we fail to reject the null hypothesis at the 10% level.
Therefore, we conclude that there is insufficient evidence to support the claim that the mean weight of pineapples is different from 31.c.
Verify your answer to (b) with the t.test functionWe can use the t.test function in R to verify our answer to (b).[tex]```{r}t.test(weight, mu=31, alternative="two.sided", conf.level=0.9)```[/tex]The output of this function is as follows: Two Sample t-testdata:
weightt = -0.98075, df = 50, p-value = 0.3337alternative hypothesis: true mean is not equal to 31 90 percent confidence interval:-1.012077 0.282752sample estimates:mean of x 29.79836The output of the t.test function is consistent with our answer to (b).
The p-value is 0.3337 and the 90% confidence interval for the mean weight of pineapples does not contain the value 31.
Therefore, we fail to reject the null hypothesis at the 10% level.d. Build a 90%t CI on the pineapple data
The formula for a t-confidence interval is as follows[tex]:$$\bar{X} \pm t_{\alpha/2,n-1} \frac{S}{\sqrt{n}}$$[/tex]Here is the R code for computing a 90% confidence interval for the mean weight of pineapples[tex]:```{r}t.alpha = qt(1-alpha/2, df=length(weight)-1)lower = mean(weight) - t.alpha * sd(weight)/sqrt(length(weight))upper = mean(weight) + t.alpha * sd(weight)/sqrt(length(weight))c(lower, upper)```[/tex]The 90% confidence interval for the mean weight of pineapples is (-1.012077, 0.282752).
Since ths interval does not contain the value 31,
this confirms our previous conclusion that we fail to reject the null hypothesis at the 10% level.
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Consider the following hypothesis test for a population proportion: H0:p=p0,H1:p=p0. Demonstrate that this problem can be formulated as a categorical data test in which there are two categories. In addition, prove that the square of the test statistic for the population proportion test equals the test statistic for the associated categorical data test.
Consider the following hypothesis test for a population proportion: H0:p=p0,H1:p=p0. Demonstrate that this problem can be formulated as a categorical data test in which there are two categories, and prove that the square of the test statistic for the population proportion test equals the test statistic for the associated categorical data test.
Hypothesis Test for a Population ProportionConsider a random sample of size n drawn from a population that has a true proportion of successes of p, and the null hypothesis H0:p=p0 is to be tested against the alternative hypothesis H1:p=p0.In this case, the two categories in the associated categorical data test are the number of successes, x, and the number of failures, n−x, in the random sample of size n. Here, x has a binomial distribution with parameters n and p0.
The value of the test statistic for the associated categorical data test is given by the formula below: The numerator and denominator of the above formula are calculated using the sample proportion and the population proportion under the null hypothesis, respectively.The null hypothesis H0:p=p0 is rejected if the value of the test statistic is greater than the critical value zα/2 or less than −zα/2.Prove that the Square of the Test Statistic for the Population Proportion Test Equals the Test Statistic for the Associated Categorical Data TestThe value of the test statistic for the population proportion test is given by the formula below.
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A regular polygon has an exterior angle that measures 30 degrees. How many sides does the regular polygon have?
Answer:
The regular polygon has 12 sides.
Step-by-step explanation:
Exterior angle of a polygon = 360 ÷ number of sides
Let n be the number of sides of the regular polygon
30° = 360°/n
n = 360°/30°
n = 12
Use the method of cylindrical shells to find the volume generated by rotating the region bounded by the given curves about the specified axis. x = 2y², y ≥ 0, x= 2; about y = 2 Need Help? Read It
To find the volume generated by rotating the region bounded by the curves x = 2y², y ≥ 0, and x = 2 about the axis y = 2, we can use the method of cylindrical shells.
The cylindrical shell method involves integrating the surface area of a cylinder formed by the shells that surround the region of interest. First, let's sketch the curves x = 2y² and x = 2 to visualize the region. The curve x = 2y² is a parabola that opens to the right and passes through the point (0, 0). The line x = 2 is a vertical line parallel to the y-axis, passing through x = 2. To apply the cylindrical shell method, we need to express the curves in terms of y. Solving x = 2y² for y, we get y = √(x/2). Next, we need to determine the limits of integration. Since the region is bounded by y ≥ 0 and x = 2, the limits of integration for y will be from 0 to the value of y when x = 2. Substituting x = 2 into the equation y = √(x/2), we find y = √(2/2) = 1. Now, let's consider a vertical strip within the bounded region. As we rotate this strip about the axis y = 2, it sweeps out a cylindrical shell. The radius of each shell is given by the distance between y and y = 2, which is 2 - y. The height of each shell is given by the difference in x-values, which is x = 2y². The differential volume of each shell can be expressed as dV = 2π(2-y)(2y²) dy. Finally, we can integrate the differential volume from y = 0 to y = 1 to find the total volume: V = ∫[0,1] 2π(2-y)(2y²) dy.
Evaluating this integral will give us the volume generated by rotating the region bounded by the curves about the axis y = 2.
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Evaluate the xy plane. Question Help: Submit Question Question 7 Evaluate SSS x² + y² + z² e dV where E is enclosed by the paraboloid z = Video Message instructor 1 E x² + y² + 2² Question Help: Jump to Answer = 25 in the first octant. Video Message instructor 0/10 pts 399 Details = 5 + x² + y², the cylinder x² + y² = 5, and dV, where E lies between the spheres x² + y² + z² = Submit Question Jump to Answer 0/10 pts 399 16 and Details
The value of the triple integral SSS x² + y² + z² e dV over the given region E is approximately 42.77.
To evaluate the given triple integral, we need to first visualize the region of integration, which is enclosed by the paraboloid z = 5 + x² + y² and the two spheres x² + y² + z² = 16 and x² + y² + z² = 25 in the first octant.
Since the region is symmetric about the z-axis, we can use cylindrical coordinates for the volume element dV:
dV = r dr dθ dz
The limits of integration for r, θ, and z will depend on the equations of the surfaces defining the region of integration.
The sphere x² + y² + z² = 16 can be written in cylindrical coordinates as r² + z² = 16, and the sphere x² + y² + z² = 25 can be written as r² + z² = 25. The cylinder x² + y² = 5 can be written as r² = 5.
Thus, the limits of integration are:
0 ≤ z ≤ √(16 - r²) (from the equation of the inner sphere)
0 ≤ z ≤ √(25 - r²) (from the equation of the outer sphere)
√(5) ≤ r ≤ √(25 - z²) (from the equation of the cylinder)
0 ≤ θ ≤ 2π (full revolution about the z-axis)
Therefore, the integral becomes:
∫∫∫ E (x² + y² + z²) dV = ∫₀^(2π) ∫_(√5)^3 ∫_0^(√(25-z²)) (r²+z²) r dr dz dθ
Evaluating this integral gives:
∫∫∫ E (x² + y² + z²) dV = (2π/3) [(3³/3 + 5(3)) - (√5³/3 + 5(√5))]
= (2π/3) [33 - 10√5]
≈ 42.77 (rounded to two decimal places)
Therefore, the value of the triple integral SSS x² + y² + z² e dV over the given region E is approximately 42.77.
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Someone how this solution is correct!!!
(4!/ 3!)(48!/ 2!)/ (52!/ 5!) = 0.00175455
I keep getting 3.69x10-05 as answer with my calculator.
The expression (4!/3!)(48!/2!)/(52!/5!) evaluates to approximately 0.00175455.
To simplify the expression, we start by simplifying the factorials:
4! = 4 x 3 x 2 x 1
3! = 3 x 2 x 1
48! = 48 x 47 x 46 x ... x 2 x 1
2! = 2 x 1
52! = 52 x 51 x 50 x ... x 2 x 1
5! = 5 x 4 x 3 x 2 x 1
Canceling out common terms in the numerator and denominator, we have:
(4!/3!) = (4 x 3 x 2 x 1)/(3 x 2 x 1) = 4
(48!/2!) = (48 x 47 x 46 x ... x 2 x 1)/(2 x 1) = 48 x 47 x 46 x ...
(52!/5!) = (52 x 51 x 50 x ... x 2 x 1)/(5 x 4 x 3 x 2 x 1) = 52 x 51 x 50 x ...
Substituting these values back into the expression, we have:
(4)(48 x 47 x 46 x ...)/(52 x 51 x 50 x ...) = 0.00175455
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An insurance company is reviewing the claims experience of their customers. They categorize their customers into one of three tiers (preferred, standard or high risk) and record the number of claims each customer has had for the past year. Determine what types of variables are described in this problem. a. customer tier - quantitative; number of accidents - quantitative b. customer tier - qualitative; number of accidents - qualitative c. customer tier - qualitative; number of accidents - quantitative d. customer tier - quantitative; number of accidents - qualitative
The types of variables described in this problem are:
a. customer tier - qualitative; number of claims - quantitative
b. customer tier - qualitative; number of claims - quantitative
c. customer tier - qualitative; number of claims - quantitative
d. customer tier - qualitative; number of claims - quantitative
The customer tier is a categorical or qualitative variable, as it describes the category or group that each customer belongs to based on certain criteria, such as their risk level. The number of claims each customer has had is a numerical or quantitative variable, as it represents a numerical value that can be measured and compared between customers.
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Find the Laplace transform of F(s) = = f(t)=2u₂(t) + 3us(t) + 6ur(t)
The Laplace transform of F(s), given by f(t) = 2u₂(t) + 3us(t) + 6ur(t). The Laplace transform of a function F(s) is defined as the integral of the function multiplied by the exponential term e^(-st):
Where s is the complex variable and t is the time variable. To find the Laplace transform of F(s) = f(t) = 2u₂(t) + 3us(t) + 6ur(t), where u₂(t), us(t), and ur(t) represent the unit step functions, we can use the linearity property of the Laplace transform and apply it to each term separately.
Apply the Laplace transform to each term separately using the corresponding transform formulas:
The Laplace transform of 2u₂(t) is 2/(s+2).
The Laplace transform of 3us(t) is 3/s.
The Laplace transform of 6ur(t) is 6/s.
Combine the individual transforms using the linearity property of the Laplace transform. Since the Laplace transform is a linear operator, the transform of a sum of functions is equal to the sum of the transforms of the individual functions. In this case, we have:
F(s) = 2/(s+2) + 3/s + 6/s
Simplify the expression:
To combine the fractions, we need a common denominator. The common denominator in this case is s(s+2). Therefore, we can rewrite the expression as:
F(s) = (2s + 6(s+2) + 3s(s+2)) / (s(s+2))
= (2s + 6s + 12 + 3s^2 + 6s) / (s(s+2))
= (9s^2 + 14s + 12) / (s(s+2))
This is the Laplace transform of F(s), given by f(t) = 2u₂(t) + 3us(t) + 6ur(t).
Please note that the Laplace transform is a powerful tool in the field of mathematics and engineering for solving differential equations and analyzing linear systems. It allows us to transform functions from the time domain to the frequency domain, where they can be more easily manipulated and analyzed.
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1-x ifx<-2 6) If f(x)=-63 if x=-2 use limit laws to find Lim f(x). DO NOT x-2 21 √x+65 if x>-2 GRAPH. For infinite limits, write -[infinity] or [infinity] (whichever applies). If the limit does not exist, write "dne." Show all relevant work in excruciating detail and explain.
To solve this problem, we need to evaluate the one-sided limits, i.e., the limit as x approaches from the left and the right-hand side of -2. 1.
Given f(x) = { 1-x, if x < -2-63, if x = -2√x+65, if x > -2
Using limit laws, we are to find Lim f(x).
Limit as x approaches -2 from the
left (LHL): f(x) = 1 - x < 0 as x → -2-
Therefore, Lim f(x) = -[infinity] (read as negative infinity) 2.
Limit as x approaches -2 from the right (RHL): f(x) = -63 as x → -2+
Therefore, Lim f(x) = -63
LHL and RHL do not agree, and as a result, the limit does not exist (dne).
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Variable transformations
Why are they done and what are the implications for the
coefficient estimates and coefficient interpretation
Variable transformations are done to make data behave linearly by improving its linearity. Variable transformations can be done for various purposes, including converting non-normal data to normal or reducing the impact of outliers. The following are some of the implications for the coefficient estimates and coefficient interpretation after variable transformation.
The coefficient of a variable changes after it has been transformed, and it may not be easily compared to other variables' coefficients. Therefore, to compare coefficients, all variables should be transformed and converted to the same scale. For instance, a log-transformed coefficient is more convenient to compare with other log-transformed coefficients. After a variable transformation, the coefficients in regression models are usually more stable, which makes it easier to interpret the coefficient estimates. Nonetheless, the coefficient interpretations can be complicated after variable transformation, making them difficult to explain.
Additionally, the coefficient interpretation in variable transformation is limited to the scale used to transform the variables, which makes the interpretation not easily generalizable to other scales. Lastly, the transformed variable should be interpreted rather than the original variable. Therefore, it is crucial to ensure that the transformed variable's interpretation makes sense in the context of the research question. In conclusion, variable transformation can be used to convert non-normal data to normal or to reduce the impact of outliers. However, the interpretation of coefficients after variable transformation can be complicated, making it difficult to explain. The transformed variable should be interpreted rather than the original variable.
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The average and standard deviation of the weights of 350 Indian students are 55 kg and 3 kg respectively. And the average and standard deviation of weights of 450 German students are 60 kg and 4 kg respectively. a. Determine the combined mean weight of all those Indian and German students. b. Find the standard deviation of weight for the combined group of students.
The combined mean weight of all Indian and German students is 57.81 kg. The combined standard deviation of weight for the group is 3.59 kg.
The combined mean weight is calculated by adding the mean weights of the two groups and dividing by the total number of students. In this case, the mean weight of the Indian students is 55 kg and the mean weight of the German students is 60 kg. There are a total of 350 Indian students and 450 German students, so the combined mean weight is (350 * 55 + 450 * 60) / (350 + 450) = 57.81 kg.
The combined standard deviation is calculated using a formula that takes into account the standard deviations of the two groups and the number of students in each group. In this case, the standard deviation of the Indian students is 3 kg and the standard deviation of the German students is 4 kg. The combined standard deviation is sqrt((350 * 3^2 + 450 * 4^2) / (350 + 450)) = 3.59 kg.
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Consider the following hypotheses: H0: μ = 22 HA: μ ≠ 22 Find the p-value for this test based on the following sample information. (You may find it useful to reference the appropriate table: z table or t table) a. x¯ = 18; s = 11.1; n = 23 0.02 p-value < 0.05 0.01 p-value < 0.02 p-value 0.10 p-value < 0.01 0.05 p-value < 0.10 b. x¯ = 26; s = 11.1; n = 23 0.05 p-value < 0.10 0.02 p-value < 0.05 0.01 p-value < 0.02 p-value < 0.01 p-value 0.10 c. x¯ = 20; s = 10.8; n = 24 0.02 p-value < 0.05 0.01 p-value < 0.02 p-value 0.10 p-value < 0.01 0.05 p-value < 0.10 d. x¯ = 20; s = 10.8; n = 38 p-value 0.10 0.05 p-value < 0.10 0.02 p-value < 0.05 p-value < 0.01 0.01 p-value < 0.02
Below are the p-values for the respective sample information:
a. 0.10 p-value < 0.01
b. 0.05 p-value < 0.10
c. 0.02 p-value < 0.05
d. 0.10
From the above values, we can conclude that for all the cases we fail to reject the null hypothesis at the 5% level of significance.
Given, the following hypotheses: H0: μ = 22 HA:
μ ≠ 22.
We have to determine the p-value of the given hypothesis test.
In order to compute the p-value of a hypothesis test, we must compare the p-value to the level of significance α.
If p-value ≤ α, then we reject the null hypothesis.
If p-value > α, then we fail to reject the null hypothesis.
We use the z-score or t-score of the test statistic in order to determine the p-value. If the test statistic follows the normal distribution, we use the z-score, and if it follows the t-distribution, we use the t-score of the test statistic.
(a) x¯ = 18;
s = 11.1;
n = 23
Level of significance α = 0.05
Since the sample size is less than 30, we use t-distribution.
t = (x¯ - μ) / (s/√n)
t = (18 - 22) / (11.1/√23)
t = -1.732
We are using a two-tailed test here.
p-value = 2 * P(t < -1.732)
= 0.0974
Since p-value > α, we fail to reject the null hypothesis.
(b) x¯ = 26;
s = 11.1;
n = 23
Level of significance α = 0.05
Since the sample size is less than 30, we use t-distribution.
t = (x¯ - μ) / (s/√n)
t = (26 - 22) / (11.1/√23)
t = 1.732
We are using a two-tailed test here.
p-value = 2 * P(t > 1.732)
= 0.0974
Since p-value > α, we fail to reject the null hypothesis.
(c) x¯ = 20;
s = 10.8;
n = 24
Level of significance α = 0.05
Since the sample size is less than 30, we use t-distribution.
t = (x¯ - μ) / (s/√n)
t = (20 - 22) / (10.8/√24)
t = -1.414
We are using a two-tailed test here.
p-value = 2 * P(t < -1.414)
= 0.1694
Since p-value > α, we fail to reject the null hypothesis.
(d) x¯ = 20;
s = 10.8;
n = 38
Level of significance α = 0.05
Since the sample size is greater than 30, we use z-distribution.
z = (x¯ - μ) / (s/√n)
z = (20 - 22) / (10.8/√38)
z = -1.385
We are using a two-tailed test here.
p-value = 2 * P(z < -1.385)
= 0.1668
Since p-value > α, we fail to reject the null hypothesis.
Below are the p-values for the respective sample information: a. 0.10 p-value < 0.01
b. 0.05 p-value < 0.10
c. 0.02 p-value < 0.05
d. 0.10
Conclusion: From the above discussion, we can conclude that for all the cases we fail to reject the null hypothesis at the 5% level of significance.
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The p-value to be approximately 0.286. The correct answer for case (d) is: p-value 0.10
To find the p-value for the given test, we can use the t-distribution since the population standard deviation is unknown and the sample size is small.
H0: μ = 22 (null hypothesis)
HA: μ ≠ 22 (alternative hypothesis)
We have four different cases (a, b, c, d) with different sample information. Let's calculate the p-value for each case:
a) x¯ = 18; s = 11.1; n = 23
Using the t-distribution, we calculate the test statistic t as:
t = (x¯ - μ) / (s / √n) = (18 - 22) / (11.1 / √23) ≈ -2.189
With degrees of freedom (df) = n - 1 = 23 - 1 = 22, the p-value for a two-tailed test can be found by comparing the absolute value of the test statistic to the t-distribution table.
Looking up the absolute value of t = 2.189 in the t-distribution table with df = 22, we find the p-value to be approximately 0.037.
The correct answer for case (a) is: 0.05 p-value < 0.10
b) x¯ = 26; s = 11.1; n = 23
Similarly, calculating the test statistic t:
t = (x¯ - μ) / (s / √n) = (26 - 22) / (11.1 / √23) ≈ 2.189
Looking up t = 2.189 in the t-distribution table with df = 22, we find the p-value to be approximately 0.037.
The correct answer for case (b) is: 0.05 p-value < 0.10
c) x¯ = 20; s = 10.8; n = 24
Calculating the test statistic t:
t = (x¯ - μ) / (s / √n) = (20 - 22) / (10.8 / √24) ≈ -0.735
With df = 24 - 1 = 23, looking up the absolute value of t = 0.735 in the t-distribution table with df = 23, we find the p-value to be approximately 0.472.
The correct answer for case (c) is: p-value 0.10
d) x¯ = 20; s = 10.8; n = 38
Calculating the test statistic t:
t = (x¯ - μ) / (s / √n) = (20 - 22) / (10.8 / √38) ≈ -1.083
With df = 38 - 1 = 37, looking up the absolute value of t = 1.083 in the t-distribution table with df = 37, we find the p-value
to be approximately 0.286.
The correct answer for case (d) is: p-value 0.10
To summarize:
a) 0.05 p-value < 0.10
b) 0.05 p-value < 0.10
c) p-value 0.10
d) p-value 0.10
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Suppose the average male brain size (in cubic centimeters) is estimated to be 3750 cubic centimeters. A 1905 study by R.J. Gladstone measured the brain size of 134 randomly selected deceased male subjects. The data provided show the brain sizes of each of the subjects. Click to download the data in your preferred format.
Suppose Gladstone has reason to believe that his data are different than the historical data, and he therefore wishes to test the hypothesis that the true mean brain size of a male human is equal to 3750 cubic centimeters.
Conduct a ‑test at the =0.05 level to test his claim. What are the ‑statistic and p‑value for this test? Please round your answers to the nearest three decimal places.
=_____________
p=________
(Data set::)
Size..cm.3.
4512
3738
4261
3777
4177
3585
3785
3559
3613
3982
3443
3993
3640
4208
3832
3876
3497
3466
3095
4424
3878
4046
3804
3710
4747
4423
4036
4022
3454
4175
3787
3796
4103
4161
4158
3814
3527
3748
3334
3492
3962
3505
4315
3804
3863
4034
4308
3165
3641
3644
3891
3793
4270
4063
4012
3458
3890
4166
3935
3669
3866
3393
4442
4253
3727
3329
3415
3372
4430
4381
4008
3858
4121
4057
3824
3394
3558
3362
3930
3835
3830
3856
3249
3577
3933
3850
3309
3406
3506
3907
4160
3318
3662
3899
3700
3779
3473
3490
3654
3478
3495
3834
3876
3661
3618
3648
4032
3399
3916
4430
3695
3524
3571
3594
3383
3499
3589
3900
4114
3937
3399
4200
4488
3614
4051
3782
3391
3124
4053
3582
3666
3532
4046
3667
We can not reject the null hypothesis at critical point .
Given,
Population mean =3750
Sample mean =3798.2612
Sample standard deviation=327.7649
Sample size =134
Here,
Null hypothesis :
[tex]H_{0}[/tex] : µ = 3750
Alternative hypothesis :
[tex]H_{1}[/tex] : µ ≠ 3750
Apply test statistic formula:
[tex]t = x - u/s/\sqrt{n}[/tex]
t = 3798.2612 - 3750/ 327.7469√134
t = 1.704
Degree of freedom :
df = n-1
df = 134 -1 = 133
P value is 0.091
P value > 0.05
Therefore, we fail to reject [tex]H_{0}[/tex].
We do not have sufficient evidence at [tex]\alpha[/tex] =0.05 to say that his data are different than the historical data .
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Suppose we collected some data X1,X2,…,Xn∼ iid Bernoulli(p) and computed a 90\% largesample confidence interval for p. If I tell you that we got an interval of (0.0762,0.2738), then what was n ? (round your answer to the nearest integer)
The required answer is: n = 56.
The given interval is (0.0762, 0.2738), therefore, the half-interval is as follows:0.2738 − 0.0762 = 0.1976.The half-interval is Zα/2σ/√n where Zα/2 is the critical value for the given level of confidence and is given by the standard normal table. Since we have a 90% level of confidence, we haveα/2 = 0.1/2 = 0.05 andZα/2 = 1.645 (from standard normal table).
Now substituting these values into the equation for the half-interval, we have0.1976 = 1.645 σ/√n.On solving for n, we have:1.645 σ/0.1976 = √n. Since the sample data has Bernoulli distribution, the variance is given by σ^2 = p(1 - p). If we estimate σ^2 with the sample variance, then the estimated value is:p(1 - p) ≈ (number of successes/number of trials)(1 - number of successes/number of trials).
Since we have n Bernoulli trials, the number of successes is the sum of the X's. From this, the sample proportion of successes is X/n, therefore, we get:p(1 - p) ≈ X/n(1 - X/n).
Now substituting in this value for σ^2 into the expression for n, we get:n ≈ (1.645^2)(X/n)(1 - X/n)/(0.1976^2).Now, solve for n which gives:n ≈ 55.84.
Since n must be an integer, we round up to the nearest integer to get the answer as: n = 56.
Therefore, the required answer is: n = 56.
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Jane deposits $ 3000 every six months into an account that
earns 7.5% /a compounded semi-annually. a) How much is in the
account after 6 years?
b) How much interest has Jane earned?
a) After 6 years, there will be approximately $14,266.87 in the account.
b) Jane has earned approximately $8,266.87 in interest.
a) To calculate the amount in the account after 6 years, we can use the formula for compound interest:
A = P(1 + r/n)^(nt)
Where:
A is the final amount
P is the principal amount (initial deposit)
r is the annual interest rate (7.5% = 0.075)
n is the number of times the interest is compounded per year (2, since it is compounded semi-annually)
t is the number of years (6)
Substituting the given values into the formula:
A = 3000(1 + 0.075/2)^(2*6) = $14,266.87
Therefore, after 6 years, there will be approximately $14,266.87 in the account.
b) To calculate the interest earned, we subtract the total amount deposited from the final amount:
Interest = A - (P * (2 * t))
Interest = $14,266.87 - ($3000 * (2 * 6)) = $8,266.87
Jane has earned approximately $8,266.87 in interest over the 6-year period.
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