To calculate the standard deviation of the sample mean (σx), we can use different formulas depending on the sample size.
(a), where n = 2000, we would use the formula σx = σ/√n.
(b), where n = 6500, we would use the formula σx = σ/√n. The population standard deviation is given as σ = 40.
(a) For case (a), where n = 2000, we use the formula σx = σ/√n. Substituting the values, we have σx = 40/√2000 ≈ 0.8944.
(b) For case (b), where n = 6500, we again use the formula σx = σ/√n. Substituting the values, we have σx = 40/√6500 ≈ 0.4977.
To calculate σx, we divide the population standard deviation (σ) by the square root of the sample size (n). This provides an estimate of the standard deviation of the sample mean. The rounded values are 0.8944 for case (a) and 0.4977 for case (b).
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Line AB and line BC form a right angle at point B. If A = (2, 5) and B = (4, 4), what is the equation of line BC?
Answer:
y = 2x - 4
Step-by-step explanation:
To solve this problem, we must first calculate the slope of the line AB using the formula:
[tex]\boxed{m = \frac{y_2 - y_1}{x_2 - x_1}}[/tex]
where:
m ⇒ slope of the line
(x₁, y₁), (x₂, y₂) ⇒ coordinates of two points on the line
Therefore, for line AB with points A = (2, 5) and B = (4, 4) :
[tex]m_{AB} = \frac{5 - 4}{2 - 4}[/tex]
⇒ [tex]m_{AB} = \frac{1}{-2}[/tex]
⇒ [tex]m_{AB} = -\frac{1}{2}[/tex]
Next, we have to calculate the slope of the line BC.
We know that the product of the slopes of two perpendicular lines is -1.
Therefore:
[tex]m_{BC} \times m_{AB} = -1[/tex] [Since BC and AB are at right angles to each other]
⇒ [tex]m_{BC} \times -\frac{1}{2} = -1[/tex]
⇒ [tex]m_{BC} = -1 \div -\frac{1}{2}[/tex] [Dividing both sides of the equation by -1/2]
⇒ [tex]m_{BC} = \bf 2[/tex]
Next, we have to use the following formula to find the equation of line BC:
[tex]\boxed{y - y_1 = m(x - x_1)}[/tex]
where (x₁, y₁) are the coordinates of a point on the line.
Point B = (4, 4) is on line BC, and its slope is 2. Therefore:
[tex]y - 4 =2 (x - 4)[/tex]
⇒ [tex]y - 4 = 2x - 8[/tex] [Distributing 2 into the brackets]
⇒ [tex]y = 2x-4[/tex]
Therefore, the equation of line BC is y = 2x - 4.
ABC high school students were surveyed. They were asked if they are currently taking C-Chemistry, B- Biology or P-Physics. The result of the survey of 95 students is summarized below. How many students take Biology and Chemistry? 11 62 5 12
There are 39 students who take Biology or Chemistry.
To find the number of students who take Biology or Chemistry, we need to determine the total number of students in the region that represents the union of Biology (B) and Chemistry (C).
We have,
P(B) = 14 (number of students taking Biology)
P(C) = 31 (number of students taking Chemistry)
P(B ∩ C) = 6 (number of students taking both Biology and Chemistry)
We can use the principle of inclusion-exclusion to find the number of students who take Biology or Chemistry:
P(B ∪ C) = P(B) + P(C) - P(B ∩ C)
= 14 + 31 - 6
= 39
Therefore, there are 39 students who take Biology or Chemistry.
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The question attached here seems to be incomplete, the complete question is attached below.
4. Let -2x+4 if x ≤ 1 f(x) = = Find the value of lim f(x), lim f(x), and lim f(x), or state that they do not exist.
lim f(x) = 2, lim f(x) = 4, and lim f(x) = DNE, The function f(x) = -2x + 4 if x ≤ 1 and 2x + 2 if x > 1 is a piecewise function.
Piecewise functions are functions that are defined by different expressions in different intervals. In this case, the function is defined by the expression -2x + 4 for x ≤ 1 and the expression 2x + 2 for x > 1.
The limit of a function is the value that the function approaches as the input approaches a certain value. In this case, we are interested in the limits of the function as x approaches 1 from the left, as x approaches 1 from the right, and as x approaches infinity.
The limit of the function as x approaches 1 from the left is the value that the function approaches as x gets closer and closer to 1 from the left. In this case, the function approaches the value 2. This is because the expression -2x + 4 is defined for all values of x that are less than or equal to 1, and the value of -2x + 4 approaches 2 as x approaches 1 from the left.
The limit of the function as x approaches 1 from the right is the value that the function approaches as x gets closer and closer to 1 from the right. In this case, the function approaches the value 4. This is because the expression 2x + 2 is defined for all values of x that are greater than 1, and the value of 2x + 2 approaches 4 as x approaches 1 from the right.
The limit of the function as x approaches infinity is the value that the function approaches as x gets larger and larger. In this case, the function approaches infinity. This is because the expression 2x + 2 grows larger and larger as x gets larger and larger.
Therefore, the limits of the function are 2, 4, and DNE.
Here is a more detailed explanation of the calculation:
The limit of a function is the value that the function approaches as the input approaches a certain value. To find the limit of a function, we can use the following steps:
Substitute the given value into the function.
If the function is defined at the given value, then the limit is the value of the function at that point.
If the function is not defined at the given value, then we can use the following methods to find the limit:
Direct substitution: If the function is defined for all values that are close to the given value, then we can substitute the given value into the function and see what value we get.
L'Hopital's rule: If the function is undefined at the given value, but the function's derivative is defined at the given value, then we can use L'Hopital's rule to find the limit.
Limits at infinity: If the function approaches a certain value as the input gets larger and larger, then we can say that the limit of the function is that value.
In this case, we are interested in the limits of the function as x approaches 1 from the left, as x approaches 1 from the right, and as x approaches infinity.
To find the limit of the function as x approaches 1 from the left, we can substitute x = 1 into the function. This gives us the value 2. Therefore, the limit of the function as x approaches 1 from the left is 2.
To find the limit of the function as x approaches 1 from the right, we can substitute x = 1 into the function. This gives us the value 4. Therefore, the limit of the function as x approaches 1 from the right is 4.
To find the limit of the function as x approaches infinity, we can see that the function approaches infinity as x gets larger and larger. Therefore, the limit of the function as x approaches infinity is infinity.
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Using the data below, what is the value of the absolute percent error for week 3? Week Time Series Value Forecast 1 7 5.00 2 5 8.00 3 4 3.00 4 3 6.00 Submit Answer format: Number: Round to: 2 decimal places.
The value of the absolute percent error for week 3 is 25.00%.
To calculate the absolute percent error for week 3, we need to find the absolute difference between the forecasted value and the actual value, and then divide it by the actual value. Finally, we multiply the result by 100 to convert it to a percentage.
To find the absolute percent error for week 3, we'll use the formula:
Absolute Percent Error = |(Actual Value - Forecasted Value) / Actual Value| * 100
For week 3:
Actual Value = 4.00
Forecasted Value = 3.00
Absolute Percent Error = |(4.00 - 3.00) / 4.00| * 100
= |1.00 / 4.00| * 100
= 0.25 * 100
= 25.00
Therefore,For week three, the absolute percent error value is 25.00%.
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A company employs 2 office workers and 6 field workers. All employee names are placed in a hat and three are chosen to form a committee. What is the probability that the committee includes both office workers?
The probability that the committee includes both office workers is 3/28 or 0.107.
There are a total of 8 employees (2 office workers + 6 field workers) in the company.
From these 8 employees, we need to choose 3 employees to form a committee.
Total Number of Possible Committees = C(8, 3)
= 8! / (3! ×(8 - 3)!) = 56
Since we want to ensure that both office workers are included in the committee, we have already chosen 2 out of the required 3 members. We need to choose 1 more member from the remaining 6 employees, which can be calculated as:
Number of Committees that Include Both Office Workers = C(6, 1) = 6
The probability that the committee includes both office workers is given by the ratio of the number of committees that include both office workers to the total number of possible committees:
Probability = Number of Committees that Include Both Office Workers / Total Number of Possible Committees
Probability = 6 / 56
Probability = 3 / 28
=0.107
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2. Two players: Adam and Bob, shoot alternately and independently of each other to a small target. Each shot costs 1 PLN. It starts with Adam, who hits with probability 1/4. Bob hits with probability of 1/3. The game ends when one of them hits - then he gets an reward. What is the probability that Adam will win this reward. 3. In the same setting as in the previous problem, calculate the expected amount of the money-PLN the players will spend on this game. More formally, if 7 denotes the number of round in which either Adam or Bob wins then the question is to find ET.
the expected amount of money the players will spend on this game is 4/9 PLN.
To calculate the probability that Adam will win the reward, we can analyze the possible scenarios and calculate the probability of each.
Let's consider the following cases:
1. Adam hits on his first turn: The probability of this happening is 1/4. In this case, Adam wins.
2. Adam misses on his first turn, but Bob also misses on his turn: The probability of this happening is (3/4) * (2/3) = 1/2. In this case, the game returns to Adam's turn.
3. Adam misses on his first turn, Bob hits on his turn: The probability of this happening is (3/4) * (1/3) = 1/4. In this case, Bob wins.
Now, considering case 2, we can break it down further:
2a. Adam misses on his second turn, and Bob misses on his second turn: The probability of this happening is (3/4) * (2/3) * (3/4) * (2/3) = 1/4. In this case, the game returns to Adam's turn.
2b. Adam misses on his second turn, but Bob hits on his second turn: The probability of this happening is (3/4) * (2/3) * (3/4) * (1/3) = 1/8. In this case, Bob wins.
Continuing this pattern, we can see that the game alternates between Adam and Bob, with the probabilities of Adam winning getting smaller each time.
By summing up the probabilities of all the cases where Adam eventually wins, we find:
P(Adam wins) = (1/4) + (1/2) * (1/4) + (1/2) * (1/4) * (1/4) + ...
This is an infinite geometric series with a common ratio of 1/4. The sum of an infinite geometric series is given by the formula:
Sum = a / (1 - r)
where a is the first term and r is the common ratio. In this case, a = 1/4 and r = 1/4.
Plugging in the values, we get:
P(Adam wins) = (1/4) / (1 - 1/4) = (1/4) / (3/4) = 1/3
Therefore, the probability that Adam will win the reward is 1/3.
Now, let's calculate the expected amount of money (in PLN) the players will spend on this game.
Let's define the random variable X as the amount of money spent on the game. We want to find E(X), the expected value of X.
We can break down the possible amounts spent on the game as follows:
- If Adam wins on his first turn, the amount spent is 1 PLN.
- If Adam wins on his second turn, the amount spent is 2 PLN.
- If Adam wins on his third turn, the amount spent is 3 PLN.
- And so on...
We can see that the amount spent is equal to the round number in which Adam wins.
Therefore, we need to calculate the expected value of the round number when Adam wins, denoted as E(7).
Using the probability calculated earlier, we have:
E(7) = 1 * P(Adam wins on his first turn) + 2 * P(Adam wins on his second turn) + 3 * P(Adam wins on his third turn) + ...
E(7) = 1 * (1/4) + 2 * (1/2) * (1/4) +
3 * (1/2) * (1/4) * (1/4) + ...
Again, this is an infinite geometric series with a common ratio of 1/4. The sum of this series is given by the formula:
Sum = a / (1 - r)^2
where a is the first term and r is the common ratio. In this case, a = 1/4 and r = 1/4.
Plugging in the values, we get:
E(7) =[tex](1/4) / (1 - 1/4)^2[/tex]
= (1/4) / [tex](3/4)^2[/tex]
= (1/4) / (9/16)
= 16/36
= 4/9
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If K = {(x, y ) | x - y = 5}, is Set K a function?
We can say that the set K is a function as it satisfies the definition of a function.
The answer is option B) Yes, K is a function. In summary, K = {(x, y) | x - y = 5} is a function because every element of the domain is related to exactly one element of the range.
Given K = {(x, y) | x - y = 5}. We need to determine whether the given set K is a function or not.
A function is a relation between two sets in which one element of the first set is related to only one element of the second set.
We can determine whether a given relation is a function or not by using the vertical line test.
In the given set K, for every value of x, there is a unique value of y such that x - y = 5. Hence, the set K can be represented as K = {(x, x - 5) | x ∈ R}.
Each element of the first set (domain) is related to exactly one element of the second set (range). In this case, for every value of x, there is a unique value of y such that x - y = 5.
Thus, we can conclude that the given set K is a function. Hence, the answer is option B) Yes, K is a function.
In summary, K = {(x, y) | x - y = 5} is a function because every element of the domain is related to exactly one element of the range.
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A concern among social scientists who study family and childhood is the effect of being raised in foster care on grown children. A study by Viner and Taylor examined the effects of childhood history of being in public care (foster care or state custody) on adult social status, particularly occupation, unemployment at age 30, income, and having been homeless since age 16. Data were from a cohort study of the 1970 British birth cohort. Data are presented in Table 2 below.
TABLE 2. Demographic Outcomes at Age 30 Years
Outcomes at age 30
Never been in public care,% (95% CI)
History of Public Care, % (95% CI)
Males:
Professional/managerial occupation (n=4489)
40% (38-41)
29% (22-37)
Currently unemployed at 30 years (n=4580)
4 % (4-5)
11% (7-17)
Income in the lowest quartile of net annual earnings for gender (n=3556)
25% (23-26)
27% (19-36)
Ever been homeless since age 16 (n=4027)
6 % (5-7)
12% (8-19)
Females:
Professional/managerial occupation (n=4830)
37% (35-38)
26% (20-33)
Currently unemployed and looking for work at 30 years (n=4942)
2% (2-2)
2% (1-6)
Income in the lowest quartile of net annual earnings for gender (n=3372)
24% (23-26)
31% (23-41)
Ever been homeless since age 16 (n=4698)
7% (6-8)
18% (13-24)
Source: Viner, Russell M. and Brent Taylor. 2005. Adult Health and Social Outcomes of Children Who Have Been in Public Care: Population-Based Study. Pediatrics 115(4): 894-899.
a. Interpret the 95% confidence intervals for the percentage of males in professional/managerial occupations for both those who were and were not in public care. What is the substantive meaning of these results?
b. Is there a significant population-level difference between males who were in care and those who were not in terms of their employment at age 30? How do you know this? (HINT: look at the confidence intervals, not the sample percentages.)
c. Are male or female subjects with a history of public care more or less likely to have ever been homeless since age 16? Be sure to cite evidence in your answer.
d. Using evidence from Table 2, what overall conclusion can you draw about the long-term effects of being in public care versus not having been in public care? Are these effects different for males and females?
(a) The 95% confidence intervals indicate that the percentage of males in professional/managerial occupations who were not in public care is estimated to be between 38% and 41%, while for those who were in public care, it is estimated to be between 22% and 37%.
(b) The overlapping confidence intervals indicate that the observed difference in sample percentages could be due to random sampling variation.
(c) Both male and female subjects with a history of public care are more likely to have ever been homeless since age 16 compared to those who were not in public care.
(d) The overall conclusion is that being in public care may have negative long-term effects on various outcomes, including occupation, unemployment, income, and homelessness.
(a) The 95% confidence intervals provide a range of values within which we can be 95% confident that the true percentage of males in professional/managerial occupations lies. For males who were not in public care, the confidence interval is 38-41%. This means that based on the sample data, we can be 95% confident that the true percentage of males in professional/managerial occupations in the population falls between 38% and 41%.
For males who were in public care, the confidence interval is 22-37%. Similarly, we can be 95% confident that the true percentage of males in professional/managerial occupations in the population falls between 22% and 37% based on the sample data.
The substantive meaning of these results is that there appears to be a difference in the percentage of males in professional/managerial occupations between those who were and were not in public care. The confidence intervals suggest that the percentage of males in professional/managerial occupations is generally higher for those who were not in public care compared to those who were.
(b) To determine if there is a significant population-level difference in employment at age 30 between males who were in care and those who were not, we need to compare the confidence intervals rather than the sample percentages. In this case, the confidence intervals for currently unemployed males at age 30 overlap: 4-5% for those not in public care and 7-17% for those in public care. Since the confidence intervals overlap, we cannot conclude that there is a significant difference in employment between the two groups at the population level. The overlapping confidence intervals indicate that the observed difference in sample percentages could be due to random sampling variation.
(c) Looking at Table 2, we can see that the percentage of males who have ever been homeless since age 16 is 6% for those not in public care and 12% for those in public care. For females, the corresponding percentages are 7% and 18%. These percentages indicate that both male and female subjects with a history of public care are more likely to have ever been homeless since age 16 compared to those who were not in public care.
(d) Based on the data presented in Table 2, we can conclude that being in public care has potential long-term effects on various outcomes. For males, being in public care is associated with lower percentages in professional/managerial occupations and higher percentages of being currently unemployed at age 30. It is also associated with a higher likelihood of having been homeless since age 16. For females, the pattern is similar, with those in public care having lower percentages in professional/managerial occupations, higher percentages in the lowest quartile of income, and a higher likelihood of having been homeless since age 16. Overall, the results suggest that being in public care may have a negative impact on social outcomes in adulthood for both males and females.
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A population grows according to an exponential growth model, with P₀= 8 and P₁ = 12.
(a) Find the common ratio R.
(b) Find P₉.
(c) Give an explicit formula for PN.
Given: P₀ = 8, P₁ = 12.Exponential growth is defined as the process in which a population increases rapidly, which leads to a greater and faster increase over time. This can be modelled using the exponential growth formula:P(n) = P₀ * rⁿWhere P₀ is the initial population, r is the common ratio and n is the number of generations or time period.(a) Finding the common ratio R.To find the common ratio, use the formula:R = P₁/P₀ ⇒ R = 12/8 ⇒ R = 3/2(b) Finding P₉.To find P₉, we can use the formula P(n) = P₀ * rⁿ.P(9) = 8 * (3/2)⁹P(9) = 8 * 19.6875P(9) = 157.5 (approx)(c) Giving an explicit formula for PN.The explicit formula for P(n) can be found as:P(n) = P₀ * rⁿP(n) = 8 * (3/2)ⁿWhere P₀ = 8 and r = 3/2.
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The following scatterplot from Rguroo output is the relationship between the percentage of students that are from the top 10% of their high school (Top_HS) and the related Median combined Math and Verbal SAT score of students (SAT) for 50 colleges in the United States. From the least squares regression line shown in the figure, above the scatterplot, the value of the slope is and the y-intercept is The value of the correlation is which mean the relationship is and
The value of the slope is 2.3486 and the y-intercept is 1089.1 . The value of the correlation is 0.50926 which means the relationship is moderate and positive.
The correlation coefficient gives the strength and direction of relationship which exists between two variables. The value of the slope also gives shows whether a positive or negative association exists between related variables.
Since the correlation coefficient is positive, then we have a positive association between the variables. Also, since the correlation coefficient is just above 0.5, then the strength of the association is moderate to strong.
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Find the absolute extrema if they exist, as well as all values of x where they occur, for the function f(x) = x + e on the domain [-1.4]. Select the correct choice below and, if necessary, fill in the answer boxes to complete your choice. OA. The absolute maximum is which occurs at x = (Round the absolute maximum to two decimal places as needed. Type an exact answer for the value of x where the maximum occurs. Use a comma to separate answers as needed.) OB. There is no absolute maximum.
To find the absolute extrema of the function f(x) = x + e on the domain [-1, 4], we need to evaluate the function at the critical points and endpoints of the domain.
First, let's check the endpoints of the domain: f(-1) = -1 + e ≈ 1.718; f(4) = 4 + e ≈ 5.718. Now, let's find the critical point by taking the derivative of f(x) and setting it equal to zero: f'(x) = 1. Setting f'(x) = 0, we find that the derivative is always nonzero. Therefore, there are no critical points within the domain [-1, 4]. Comparing the values at the endpoints and the absence of critical points, we can see that the function is monotonically increasing within the domain. Therefore, the maximum value of the function occurs at the right endpoint, x = 4. The absolute maximum value of the function is approximately 5.718, and it occurs at x = 4.
Therefore, the correct choice is: OA. The absolute maximum is 5.718, which occurs at x = 4.
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When flights are delayed, do two of the worst airports experience delays of the same length? Suppose the delay times in minutes for seven recent, randomly selected delayed flights departing from each of these airports are as follows.
Airport 1 Airport 2
62 106
91 36
43 39
37 84
59 75
26 47
41 54
Use the MWW test to determine if there is a difference in length of flight delays for these two airports. Use α = 0.05.
State the null and alternative hypotheses.
H0: The two populations of flight delays are identical.
Ha: The two populations of flight delays are not identical.H0: Median delay time for airport 1 − Median delay time for airport 2 ≥ 0
Ha: Median delay time for airport 1 − Median delay time for airport 2 < 0 H0: Median delay time for airport 1 − Median delay time for airport 2 < 0
Ha: Median delay time for airport 1 − Median delay time for airport 2 = 0H0: The two populations of flight delays are not identical.
Ha: The two populations of flight delays are identical.H0: Median delay time for airport 1 − Median delay time for airport 2 ≤ 0
Ha: Median delay time for airport 1 − Median delay time for airport 2 > 0
Find the value of the test statistic.
W =
What is the p-value? (Round your answer to four decimal places.)
p-value =
What is your conclusion?
Reject H0. There is sufficient evidence to conclude that there is a significant difference in length of flight delays for these two airports
.Reject H0. There is not sufficient evidence to conclude that there is a significant difference in length of flight delays for these two airports.
Do not reject H0. There is not sufficient evidence to conclude that there is a significant difference in length of flight delays for these two airports.
Do not reject H0. There is sufficient evidence to conclude that there is a significant difference in length of flight delays for these two airports.
When flights are delayed, do two of the worst airports experience delays of the same length?
Suppose the delay times in minutes for seven recent, randomly selected delayed flights departing from each of these airports are as follows.
The median is the middle value of a set of data;
the Mann-Whitney-Wilcoxon (MWW) test is a nonparametric technique for determining whether the two populations are the same or different. The null hypothesis (H0) is that the population medians are equal; the alternate hypothesis (Ha) is that they are not equal. Let us first identify the null and alternate hypotheses, and then we will compute the value of the test statistic W and the p-value, which will be used to make a decision.
Null Hypothesis (H0):
The two populations of flight delays are identical. Alternate Hypothesis (Ha): The two populations of flight delays are not identical. The test statistic is calculated using the formula:
W = smaller of W1 and W2, where W1 and W2 are the sums of the ranks of the delay times of Airport 1 and Airport 2, respectively.
The values of W1 and W2 are 45 and 66, respectively.
W = smaller of W1 and W2 = 45.
The p-value is computed using the following formula:
p-value = P(W ≤ 45) = 0.0221 (to four decimal places).
Since p-value (0.0221) < α (0.05), we reject the null hypothesis (H0) and conclude that there is sufficient evidence to conclude that there is a significant difference in length of flight delays for these two airports.
Therefore, the correct option is: Reject H0. There is sufficient evidence to conclude that there is a significant difference in length of flight delays for these two airports.
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Mall security estimates that the average daily per-store theft is at least $1000, but wants to determine the accuracy of this statistic. The company researcher takes a sample of 81 theft cases and finds that =$990 and s = $20.
a) Test at α = .10
Step 1: Hypothesis
Step 2: Critical value and non-rejection range
Step3: Compute test-value (calculated z)
Step 4: Reject or not reject (explain what that means)
b – independent from a) Construct a 90% CIE of μ
Based on the given data, the hypothesis testing results suggest that there is enough evidence to reject the null hypothesis and conclude that the average daily per-store theft is less than $1000. The calculated z-value of -4.5 falls within the non-rejection range, indicating a significant difference. Additionally, a 90% confidence interval for the population mean is estimated to be approximately 982.74 to 997.26.
a) Hypothesis Testing:
Hypotheses:
Null Hypothesis (H0): The average daily per-store theft is $1000.
Alternative Hypothesis (Ha): The average daily per-store theft is less than $1000.
Critical value and non-rejection range:
Since we are testing at α = 0.10 (10% significance level) and the alternative hypothesis is one-sided (less than), we need to find the critical z-value that corresponds to the desired significance level. In this case, the critical z-value is approximately -1.28.
Non-rejection range: If the calculated z-value falls within the range greater than or equal to -1.28, we fail to reject the null hypothesis.
Compute test-value (calculated z):
The calculated z-value can be calculated using the formula:
z = (X - μ) / (s / √n)
where X is the sample mean, μ is the hypothesized population mean, s is the sample standard deviation, and n is the sample size.
Substituting the values:
z = (990 - 1000) / (20 / √81)
z = -10 / (20 / 9)
z = -10 * (9 / 20)
z = -4.5
Reject or not reject:
Since the calculated z-value (-4.5) is less than the critical z-value (-1.28) and falls within the non-rejection range, we reject the null hypothesis. There is enough evidence to suggest that the average daily per-store theft is less than $1000.
b) Confidence Interval Estimation (CIE):
To construct a 90% confidence interval for the population mean (μ), we can use the formula:
CI = X ± (z * (s / √n))
where X is the sample mean, s is the sample standard deviation, n is the sample size, and z is the critical value corresponding to the desired confidence level.
Substituting the values:
CI = 990 ± (1.645 * (20 / √81))
CI = 990 ± (1.645 * (20 / 9))
CI ≈ 990 ± 7.26
The 90% confidence interval for the population mean (μ) is approximately 982.74 to 997.26.
Note: The confidence interval estimates the range in which we can be 90% confident that the true population mean falls.
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A data set about speed dating includes "like" ratings of male dates made by the female dates. The summary statistics are
n=184,
x=7.51,
s=2.07.
Use a
0.05
significance level to test the claim that the population mean of such ratings is less than
8.00.
Assume that a simple random sample has been selected. Identify the null and alternative hypotheses, test statistic, P-value, and state the final conclusion that addresses the original claim.
The null hypothesis (H0) is that the population mean of "like" ratings is equal to 8.00, while the alternative hypothesis (Ha) is that the population mean is less than 8.00. With a significance level of 0.05, the test statistic, P-value, and final conclusion can be determined based on the provided summary statistics.
The null hypothesis (H0) states that the population mean of "like" ratings is equal to 8.00. The alternative hypothesis (Ha) states that the population mean is less than 8.00. Therefore, the hypotheses can be stated as follows:
H0: μ = 8.00
Ha: μ < 8.00
To test these hypotheses, we need to calculate the test statistic and the P-value. The test statistic for a one-sample t-test can be calculated using the formula:
t = (x - μ) / (s / √n)
where x is the sample mean, μ is the hypothesized population mean, s is the sample standard deviation, and n is the sample size.
Substituting the given values into the formula, we have:
t = (7.51 - 8.00) / (2.07 / √184)
= -0.49 / (2.07 / √184)
= -0.49 / (2.07 / 13.56)
= -0.49 / 0.152
= -3.224
Next, we need to find the P-value associated with this test statistic. The P-value represents the probability of obtaining a test statistic as extreme as the observed one, assuming the null hypothesis is true.
Using a t-distribution table or statistical software, we find that the P-value for a t-statistic of -3.224 with 183 degrees of freedom is less than 0.001 (highly significant).
In hypothesis testing, the null hypothesis (H0) represents the claim or assumption to be tested, while the alternative hypothesis (Ha) represents the assertion opposite to the null hypothesis. The significance level, denoted by α, is the threshold used to determine the statistical significance of the results.
To test the claim that the population mean of "like" ratings is less than 8.00, we set up the null hypothesis (H0) as μ = 8.00 and the alternative hypothesis (Ha) as μ < 8.00. By calculating the test statistic and the P-value, we can evaluate the evidence against the null hypothesis.
Using the given summary statistics, we calculated the test statistic t to be -3.224. Comparing this value to the critical value for a one-tailed test at a 0.05 significance level, we found that the P-value associated with the test statistic is less than 0.001.
Since the P-value is less than the significance level, we reject the null hypothesis. This means that we have enough evidence to conclude that the population mean of "like" ratings is less than 8.00.
In summary, based on the provided data and significance level of 0.05, the analysis suggests strong evidence to support the claim that the population mean of "like" ratings by female dates is less than 8.00.
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find the critical points please
6. f(x) = √²-4 7. f(x) = 3x + 2) - 1
The critical points are defined as those points on the function where its derivative either becomes zero or undefined.
Let's find the critical points of the given functions below:1. f(x) = √²-4
Firstly, let's simplify the expression inside the square root:² - 4 = 4 - 4 = 0
So, the function becomes:f(x) = √0The only critical point is at x = 0, where the function changes from positive to negative.2. f(x) = 3x + 2) - 1
The derivative of the given function is:f'(x) = 3
As we see, the derivative of the function is always positive, which means there are no critical points. Hence, the function f(x) = √²-4 has a critical point at x = 0, and the function f(x) = 3x + 2) - 1 has no critical points.
Finding critical points is an important aspect of determining the local maximums and minimums of a given function.
A critical point occurs where the derivative of a function becomes zero or undefined. The given functions are f(x) = √²-4 and f(x) = 3x + 2) - 1. Simplifying the expression inside the square root in the first function gives us f(x) = √0. Thus, the only critical point is at x = 0, where the function changes from positive to negative. The derivative of the second function is f'(x) = 3, which is always positive, indicating no critical points. Therefore, the function f(x) = √²-4 has a critical point at x = 0, and the function f(x) = 3x + 2) - 1 has no critical points.
Thus, the conclusion is that the critical points of the given functions are x = 0 and none, respectively.
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You are testing the claim that the proportion of men who own cats is significantly different than the proportion of women who own cats.
You sample 150 men, and 30% own cats.
You sample 70 women, and 10% own cats.
A hypothesis test is required to examine the veracity of the argument that the proportion of men who own cats is substantially distinct from the proportion of women who own cats.
The null and alternative hypotheses for this two-proportion z-test are as follows:The null hypothesis states that there is no significant difference between the proportion of men who own cats and the proportion of women who own cats. The alternative hypothesis argues that the proportion of men who own cats is significantly different from the proportion of women who own cats.
The sample proportions and sample sizes for each group can be used to calculate the test statistic, which is a standard normal distribution with a mean of 0 and a standard deviation of . In this example, the p-value is less than 0.005, implying that we reject the null hypothesis at the 5% level of significance since it is highly unlikely that we would observe a test statistic this large if the null hypothesis were true.
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Given a differentiable function f(x,y), which of the following are correct statements about the directional derivative D u f at a point (x0, y0)Select all that apply.
(a): D u f(x0, y0)=f(x0, y0) times u
(b): u is a unit vector
(c): D u f(x0, y0) is always a positive number
(d): the maximum directional derivative of f at (x0,y0) is f(x0,y0)
The correct statements about the directional derivative Du f at a point (x0, y0) are: (a) Duf(x0, y0) = f(x0, y0) times u, and (b) u is a unit vector.
The directional derivative Du f measures the rate at which the function f changes with respect to a given direction u at a specific point (x0, y0).
Statement (a) is correct. The directional derivative Duf(x0, y0) is equal to the dot product of the gradient of f at (x0, y0) and the unit vector u. Therefore, Duf(x0, y0) can be expressed as f(x0, y0) times u, where f(x0, y0) is the magnitude of the gradient of f at (x0, y0).
Statement (b) is also correct. The vector u represents the direction in which the derivative is calculated. To ensure that the directional derivative is independent of the length of u, it is commonly chosen as a unit vector, meaning it has a magnitude of 1.
Statements (c) and (d) are incorrect. The value of Duf(x0, y0) can be positive, negative, or zero, depending on the direction of u and the behavior of the function f. It is not always a positive number. Additionally, the maximum directional derivative of f at (x0, y0) is not necessarily equal to f(x0, y0). The maximum directional derivative occurs in the direction of the gradient of f, which may not align with the direction given by u.
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A mountain climber is about to haul up a 20-m length of hanging rope. How much work will it take if the rope weighs 0.7 N/m ? The amount of work required is (Type an integer or a decimal.)
The work required to haul up the 20-meter length of hanging rope can be calculated by multiplying the weight of the rope per unit length by the length of the rope.
The amount of work required is equal to the force exerted on the rope multiplied by the distance over which the force is applied.
Given that the weight of the rope is 0.7 N/m, we can calculate the work as follows:
Work = Force × Distance
Since the force is the weight per unit length, we can substitute the values:
Work = (0.7 N/m) × (20 m)
Simplifying the expression, we find:
Work = 14 N
Therefore, the amount of work required to haul up the 20-meter length of hanging rope is 14 N.
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: Find the equation of the parabola with the given properties Vertex (0, 0), focus (4,0). = x
The equation of the parabola is x^2 = 16y.
To find the equation of the parabola with the given properties, we can use the standard form of the equation of a parabola:
(x - h)^2 = 4p(y - k),
where (h, k) represents the vertex of the parabola and p is the distance from the vertex to the focus (and also the distance from the vertex to the directrix).
In this case, the vertex is given as (0, 0) and the focus is given as (4, 0). Since the vertex is at the origin (0, 0), we have h = 0 and k = 0.
The distance from the vertex to the focus is given as 4, which means p = 4.
Substituting these values into the standard form equation, we have:
(x - 0)^2 = 4(4)(y - 0).
Simplifying further:
x^2 = 16y.
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Tossing Coins Find the mean, variance, and standard deviation for the number of heads when 13 coins are tossed. Round your answers to three decimal places, (a) Find the mean. Mean: μ= (b) Find the variance and standard deviation. Variance: σ^2=
Standard deviation:0 =
(a) Mean: μ = 6.500
(b) Variance: σ^2 = 3.828, Standard deviation: σ = 1.957
When tossing 13 coins, each coin has two possible outcomes: heads or tails. Assuming a fair coin, the probability of getting a head is 1/2, and the probability of getting a tail is also 1/2.
To find the mean, we multiply the number of coins (13) by the probability of getting a head (1/2). Thus, the mean is given by:
Mean (μ) = Number of coins × Probability of getting a head
= 13 × 1/2
= 6.500 (rounded to three decimal places)
To find the variance, we need to calculate the squared difference between the number of heads and the mean for each possible outcome, and then multiply it by the probability of that outcome.
Summing up these values gives us the variance. Since the variance measures the spread or dispersion of the data, the square root of the variance gives us the standard deviation.
Variance (σ^2) = ∑ [ (x - μ)^2 × P(x) ]
= ∑ [ (x - 6.500)^2 × P(x) ]
= (0 - 6.500)^2 × 13C0 × (1/2)^13 + (1 - 6.500)^2 × 13C1 × (1/2)^13 + ... + (13 - 6.500)^2 × 13C13 × (1/2)^13
≈ 3.828 (rounded to three decimal places)
Standard deviation (σ) = √Variance
≈ √3.828
≈ 1.957 (rounded to three decimal places)
Therefore, the mean number of heads when tossing 13 coins is 6.500. The variance is approximately 3.828, and the standard deviation is approximately 1.957.
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Tickets for a raffle cost $ 20. There were 601 tickets sold. One ticket will be randomly selected as the winner, and that person wins $ 1900 and also the person is given back the cost of the ticket. For someone who buys a ticket, what is the Expected Value (the mean of the distribution)? If the Expected Value is negative, be sure to include the "-" sign with the answer. Express the answer rounded to two decimal places. Expected Value = $
The expected value for someone who buys a ticket cost is approximately -$16.78.
To calculate the expected value, we need to multiply each outcome by its respective probability and sum them up. Let's break down the calculations:
Probability of winning: Since there are 601 tickets sold and only one winner, the probability of winning is 1/601.
Value of winning: The winner receives $1900 in addition to getting the cost of the ticket back, which is $20. So the total value of winning is $1900 + $20 = $1920.
Value of losing: If you don't win, you lose the $20 cost of the ticket.
Now we can calculate the expected value:
Expected Value = (Probability of winning) * (Value of winning) + (Probability of losing) * (Value of losing)
Expected Value = (1/601) * $1920 + (600/601) * (-$20)
Calculating this expression:
Expected Value ≈ ($1920/601) - ($12000/601) ≈ $3.19 - $19.97 ≈ -$16.78
Therefore, the expected value for someone who buys a ticket is approximately -$16.78.
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The latitude (L) and the average temperatures in February (T) in degrees Celsius (∘C) of 10 world cities were measured. The calculated least squares linear regression model for this data was: T=35.7−0.713(L) a. The slope is which interprets b. The relationship between latitude (L) and the average temperatures (T) of these 10 world cities is This means c. If in fact the average temperature (T) for these 10 world cities is 10 degrees Celsius (∘C) for a latitude of 40 , the residual is which means we have
a) Regression model is -0.713.
b) The average temperature decreases.
c) The residual in this case is approximately 2.82. This means that the observed temperature at a latitude of 40 is 2.82 degrees Celsius lower than the predicted temperature based on the linear regression model.
a. The slope of the linear regression model is -0.713.
b. The relationship between latitude (L) and average temperatures (T) of these 10 world cities is negative. As latitude increases, the average temperature decreases.
c. If the average temperature (T) for these 10 world cities is 10 degrees Celsius at a latitude of 40, we can calculate the residual as the difference between the predicted temperature and the actual temperature:
Residual = Observed temperature - Predicted temperature
Observed temperature = 10 degrees Celsius
Predicted temperature = 35.7 - 0.713(L)
Substituting the values:
Residual = 10 - (35.7 - 0.713(40))
Calculating the residual:
Residual = 10 - (35.7 - 28.52)
Residual = 10 - 7.18
Residual ≈ 2.82
Therefore, the residual in this case is approximately 2.82. This means that the observed temperature at a latitude of 40 is 2.82 degrees Celsius lower than the predicted temperature based on the linear regression model.
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Suppose X is a binomial random variable such
that n = 15 and p =
0.33 , then,
the mean, μ, and standard deviation o respectively are μ = μ = = 1.155, o = 1.291 7.014, o = 3.211 Ο μ = 1.333, σ 4.620, o = = 1.760 = 1.672
X is a binomial random variable such that n = 15 and p = 0.33, the mean, μ, and standard deviation σ respectively are;μ = np = 15 x 0.33 = 4.95σ = √npq = √15 x 0.33 x (1 - 0.33)σ = 1.805
In probability theory and statistics, the binomial distribution with parameters n and p is the discrete probability distribution of the number of successes in a sequence of n independent experiments, each asking a yes-no question, and each with its own Boolean-valued outcome: a random variable containing binary data.A binomial random variable is a count of the number of successes in a binomial experiment. Here, suppose X is a binomial random variable such that n = 15 and p = 0.33, then, the mean and standard deviation are calculated. In this case, the mean, μ, and standard deviation σ are;μ = np = 15 x 0.33 = 4.95σ = √npq = √15 x 0.33 x (1 - 0.33)σ = 1.805
Therefore, the mean is 4.95 and the standard deviation is 1.805.
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Determine the equation of the line tangent to the curve f(x)=cot²x at x = A>O. The value of A is The value of Bis The value of C is The value of Dis HA in general form Ax+By+C+D=0 where
The equation of the tangent line is Ax + By + C + D = 0, where A = 2cot(A), B = 1, C = 0, and D = 0. To determine the equation of the line tangent to the curve f(x) = cot²x at x = A, we need to find the derivative of the function and evaluate it at x = A.
The equation of the tangent line will be in the form Ax + By + C + D = 0. The values of A, B, C, and D can be determined by substituting the values into the equation. The derivative of f(x) = cot²x can be found using the chain rule. Let's denote g(x) = cot(x), then f(x) = g(x)². The derivative of g(x) with respect to x is given by g'(x) = -csc²(x). Applying the chain rule, the derivative of f(x) = cot²x is: f'(x) = 2g(x)g'(x) = 2cot(x)(-csc²(x)) = -2cot(x)csc²(x)
Now, we evaluate the derivative at x = A: f'(A) = -2cot(A)csc²(A)
The equation of the tangent line can be written in the form Ax + By + C + D = 0. Since the slope of the line is given by f'(A), we have:
A = -2cot(A)
B = 1
C = 0
D = 0
Therefore, the equation of the tangent line to the curve f(x) = cot²x at x = A is: -2cot(A)x + y = 0
This equation can also be written as: 2cot(A)x - y = 0
So, the equation of the tangent line is Ax + By + C + D = 0, where A = 2cot(A), B = 1, C = 0, and D = 0.
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The base of a solid is bounded by the parabola y=4−x 2
and the x-axis. The cross sections perpendicular to the x-axis are rectangles with height equal to the twice the length of base. Which of the following integrals represents the volume of the solid? ∫ −2
2
2x(4−x 2
) 2
dx ∫ −2
2
π(4−x 2
) 2
dx ∫ −2
2
2(4−x 2
) 2
dx ∫ −2
2
(4−x 2
)dx ∫ −2
2
(4−x 2
) 2
dx
We have: y = 2xSince the limits of integration are -2 and 2, the definite integral becomes[tex]V = ∫_(-2)^2▒2y dx = ∫_(-2)^2▒4x dx = 2∫_(-2)^2▒x dx= 2[x^2 / 2] _(-2)^2= 2[2^2 / 2 - (-2)^2 / 2] = 8[/tex] Hence, the volume of the solid is 8 square units.
A solid is bounded by the parabola y=4−x^2 and the x-axis. The cross sections perpendicular to the x-axis are rectangles with a height equal to twice the length of the base. It is known that the height of each rectangle is equal to twice the length of the base.
Hence, the height of each rectangle is equal to 2 × y. The length of the base of each rectangle is equal to the difference between the x-coordinates of the right and left edges of the rectangle. As the cross-sections are perpendicular to the x-axis, the width of the rectangle is equal to dx.
Therefore, the area of each cross-section of the solid is equal to A = 2y × dx. Hence, the volume of the solid is the definite integral of A concerning x from [tex]x = -2 to x = 2. V = ∫_(-2)^2▒A dxV = ∫_(-2)^2▒2y dx[/tex]We need to determine y in terms of x so that we can substitute it into the formula to calculate V. Here, the base of the solid is bounded by the parabola y=4−x^2 and the x-axis. The x-axis is the line y = 0. Thus, we have: y = 2xSince the limits of integration are -2 and 2, the definite integral becomes[tex]V = ∫_(-2)^2▒2y dx = ∫_(-2)^2▒4x dx = 2∫_(-2)^2▒x dx= 2[x^2 / 2] _(-2)^2= 2[2^2 / 2 - (-2)^2 / 2] = 8[/tex]
Hence, the volume of the solid is 8 square units.
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: Solve the Cauchy-Euler equation t'y' - 9ty' + 21y = 0 with initial conditions y(1) = -3, y'(1) = 3. y(t)
The solution to the Cauchy-Euler equation t'y' - 9ty' + 21y = 0 with initial conditions y(1) = -3 and y'(1) = 3 is y(t) = t^3 - 2t^2 + t.
This solution is obtained by assuming y(t) = t^m and solving the corresponding characteristic equation. The initial conditions are then used to determine the specific values of the constants involved in the general solution.
To solve the Cauchy-Euler equation t'y' - 9ty' + 21y = 0, we assume a solution of the form y(t) = t^m. By substituting this into the equation, we get the characteristic equation m(m-1) - 9m + 21 = 0. Solving this quadratic equation, we find two distinct roots: m = 3 and m = 7.
The general solution is then expressed as y(t) = c1 * t^3 + c2 * t^7, where c1 and c2 are constants to be determined. To find these constants, we use the initial conditions y(1) = -3 and y'(1) = 3.
Plugging in t = 1 and y(1) = -3 into the general solution, we obtain -3 = c1 * 1^3 + c2 * 1^7, which simplifies to c1 + c2 = -3. Next, we differentiate the general solution to find y'(t) = 3c1 * t^2 + 7c2 * t^6. Evaluating this expression at t = 1 and y'(1) = 3 gives 3 = 3c1 + 7c2.
Solving the system of equations formed by these two equations, we find c1 = -2 and c2 = 1. Substituting these values back into the general solution, we obtain the specific solution y(t) = t^3 - 2t^2 + t, which satisfies the Cauchy-Euler equation with the given initial conditions.
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Answer the following questions. I am not looking for mathematical answers; I want you to reason through the questions and use your intuition to answer them. (a) (10 points) What are the differences between the Baumol-Tobin and Money in the Utility Function models of money demand? (b) (10 points) Why did Milton Friedman argue for a 0\% nominal interest rate? (c) (10 points) True/False/Uncertain (and explain why): Wage growth resulting from an increase in expected inflation is a sign, not the cause, of inflation. (d) (10 points) True/False/Uncertain (and explain why): If the central bank buys $10 million worth of securities, then the money supply will increase by exactly $10 million. (e) (10 points) True/False/Uncertain (and explain why): The Taylor Rule is used as a "rule of thumb" rather than an explicit rule in central banking.
a) Baumol-Tobin model of money demand is based on the transaction costs. b)Milton Friedman argued for a 0% nominal interest rate as he believed that the nominal interest. c)True. Wage growth resulting from an increase in expected inflation is a sign. d)Uncertain. The money supply may not increase by exactly $10 million if the central bank buys $10 million worth of securities. e) False. The Taylor Rule is an explicit rule in central banking that provides guidance on setting the policy
a) Baumol-Tobin model of money demand is based on the transaction costs of converting non-monetary assets into money and vice versa.
Whereas, the Money in the Utility Function model of money demand is based on the utility of holding money as a store of value and the opportunity cost of holding non-monetary assets.
b) Milton Friedman argued for a 0% nominal interest rate as he believed that the nominal interest rate should reflect the real rate of return and expected inflation, and a 0% nominal interest rate would help stabilize the economy by reducing fluctuations in the nominal interest rate.
c) True. Wage growth resulting from an increase in expected inflation is a sign, not the cause, of inflation. An increase in expected inflation can lead to an increase in nominal wages, but this increase in nominal wages does not cause inflation. Instead, inflation is caused by an increase in the money supply.
d) Uncertain. The money supply may not increase by exactly $10 million if the central bank buys $10 million worth of securities. This is because the central bank may purchase securities from a bank that already has excess reserves, which would not increase the money supply.
e) False. The Taylor Rule is an explicit rule in central banking that provides guidance on setting the policy interest rate based on the output gap and inflation deviation from target.
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The average number of accidents at controlled intersections per year is 5. Is this average more for intersections with cameras installed? The 55 randomly observed intersections with cameras installed had an average of 5.3 accidents per year and the standard deviation was 1.2. What can be concluded at the αα = 0.05 level of significance?
For this study, we should use Select an answer t-test for a population mean z-test for a population proportion
The null and alternative hypotheses would be:
H0:H0: ? μ p Select an answer > ≠ < =
H1:H1: ? μ p Select an answer > < ≠ =
H0: The average number of accidents at intersections with cameras installed is the same as the average number of accidents at all controlled intersections (μ = 5)
H1: The average number of accidents at intersections with cameras installed is greater than the average number of accidents at all controlled intersections (μ > 5)
For this study, we should use a t-test for a population mean since we are comparing the means of two independent samples.
The null and alternative hypotheses would be:
H0: The average number of accidents at intersections with cameras installed is the same as the average number of accidents at all controlled intersections (μ = 5)
H1: The average number of accidents at intersections with cameras installed is greater than the average number of accidents at all controlled intersections (μ > 5)
We are testing whether the average number of accidents at intersections with cameras installed is higher than the overall average of 5. Therefore, the alternative hypothesis is one-sided (μ > 5).
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What is the optimal time for a scuba diver to be on the bottom of the ocean? That depends on the depth of the dive. The U.S. Navy has done a lot of research on this topic. The Navy defines the "optimal time" to be the time at each depth for the best balance between length of work period and decompression time after surfacing. Let x = depth of dive in meters, and let y = optimal time in hours. A random sample of divers gave the following data.
x 15.1 26.3 31.2 38.3 51.3 20.5 22.7
y 2.68 1.98 1.58 1.03 0.75 2.38 2.20
(a) Find Σx, Σy, Σx^2, Σy^2, Σxy, and r. (Round r to three decimal places.)
Σx = Σy = Σx^2 = Σy^2 = Σxy = r = (c) Find a, and b. (Round your answers to four decimal places.)
a = b = (d) Find the predicted optimal time in hours for a dive depth of x = 33 meters. (Round your answer to two decimal places.)
hr
(f) Use a 1% level of significance to test the claim that < 0. (Round your answers to two decimal places.) Hint 1: The standard error of b is 0.005413. Hint 2: Your answers to the t and critical t should have the same sign.
t = critical t = Conclusion
Fail to reject the null hypothesis. There is sufficient evidence that < 0.Reject the null hypothesis. There is insufficient evidence that < 0. Fail to reject the null hypothesis. There is insufficient evidence that < 0.Reject the null hypothesis. There is sufficient evidence that < 0.
a) The values of Σx, Σy, Σx², Σy², Σxy, and r are found.
b) b ≈ 3.3166: a -8.2109
c) The predicted optimal time = 2.62 hours
d) We reject the null hypothesis. There is sufficient evidence that < 0.
(a) We are given the following data:
x 15.1 26.3 31.2 38.3 51.3 20.5 22.7
y 2.68 1.98 1.58 1.03 0.75 2.38 2.20
Now, we have to find Σx, Σy, Σx², Σy², Σxy, and r.
Σx = 205.4
Σy = 12.6
Σx² = 8,797.67
Σy² = 18.9020
Σxy = 541.341
r = Σxy/√(Σx² Σy²)
= 541.341/√(8,797.67 × 18.9020)
≈ 0.881
(b) We need to find the values of a and b.
Using the formula, we get:
b = r (sy/sx)
= (0.881 × 0.5261)/0.1408
≈ 3.3166
a = y¯ - bx¯
= 1.8364 - (3.3166 × 27.9143)
≈ -8.2109
(c) We are supposed to find the predicted optimal time in hours for a dive depth of x = 33 meters
For x = 33 meters, the predicted optimal time is:
y = a + bx = -8.2109 + (3.3166 × 33)
≈ 2.6178
≈ 2.62 hours
(d) We are to test the claim that < 0 using a 1% level of significance.
The null and alternate hypotheses are:
H0: ≥ 0
Ha: < 0
The standard error of b is 0.005413.
The test statistic is:
t = (b - 0)/0.005413
= 3.3166/0.005413
≈ 612.4210
At α = 0.01 level of significance, the critical values are -2.998 and 2.998.
Since t > 2.998, we reject the null hypothesis.
There is sufficient evidence that < 0.
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The number of pizzas consumed per month by university students is normally diatributed with a mean- of 12 and a standard deviation of 2. A. Whit proportion of students consume more than 13 pizzas per month? Probability * 9. What is the probability that in a random sample of size 12. a total of more than 168 pizzas are consumed? (Hint: What is the mean number of pizzas consurmed by the sample of 12 students? Probability =
The proportion of students consuming more than 13 pizzas per month is approximately 0.6915. The probability that in a sample of size 12, a total of more than 168 pizzas are consumed is approximately 1.
(a) To find the proportion of students who consume more than 13 pizzas per month, we can use the standard normal distribution. First, we need to calculate the z-score for 13 pizzas using the formula:
z = (x - μ) / σ
where x is the value we want to find the proportion for (13), μ is the mean (12), and σ is the standard deviation (2).
z = (13 - 12) / 2 = 0.5
Next, we can use a standard normal distribution table or a calculator to find the proportion corresponding to the z-score of 0.5. From the table or calculator, we find that the proportion is approximately 0.6915.
Therefore, the proportion of students who consume more than 13 pizzas per month is approximately 0.6915.
(b) To find the probability that in a random sample of size 12, a total of more than 168 pizzas are consumed, we need to consider the distribution of the sample mean.
The mean number of pizzas consumed by the sample of 12 students would be the same as the mean of the population, which is 12. However, the standard deviation of the sample mean (also known as the standard error) is given by σ / √n, where σ is the population standard deviation (2) and n is the sample size (12).
Standard error = 2 / √12 ≈ 0.577
We can now calculate the z-score for the total number of pizzas consumed in the sample of 12 students using the formula:
z = (x - μ) / σ
where x is the value we want to find the probability for (more than 168 pizzas), μ is the mean (12), and σ is the standard error (0.577).
z = (168 - 12) / 0.577 ≈ 272.59
Since we want to find the probability of a total of more than 168 pizzas consumed, we can find the proportion corresponding to the z-score of 272.59 using a standard normal distribution table or a calculator. The probability is extremely close to 1 (or 100%).
Therefore, the probability that in a random sample of size 12, a total of more than 168 pizzas are consumed is approximately 1.
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