Question 1

The average score of a sample of 30 students on their second statistics examination was 85 with a standard deviation of 11.Is the variance of the population significantly more than 80? Use a .05 level of significance.

Accepted Answer

The answer of The average score of a sample of...

Question 2

A sample of 22 bottles of soft drink showed a variance of .64 in their contents.At the 5% level, determine whether or not the standard deviation of the population is significantly different from .7 ounces.Use the critical value approach.

Accepted Answer

The answer of A sample of 22 bottles of soft...

Question 3

A sample of 30 items provided a sample mean of 28 and a sample standard deviation of 6.Test the following hypotheses using α = .05.What is your conclusion? H₀: σ² ≤ 25 H_a: σ² > 25

Accepted Answer

The answer of A sample of 30 items provided a...

Question 4

The sampling distribution used when making inferences about a single population's variance is

Accepted Answer

A)  an F distribution. 
B)  a t distribution. 
C)  a chi-square distribution. 
D)  a normal distribution.

Question 5

The symbol used for the variance of the sample is

Accepted Answer

A)  σ. 
B)  σ2. 
C)  s. 
D)  s2.

Question 6

A random sample of 20 observations showed a standard deviation of 8.At a .05 level of significance, test to see if the variance of the population is significantly less than 65.Use the critical value approach.

Accepted Answer

The answer of A random sample of 20 observations showed...

Question 7

What is the 90% confidence interval estimate of a population standard deviation when a sample
variance of 50 is obtained from a sample of 15 items?

Accepted Answer

The answer of What is the 90% confidence interval estimate...

Question 8

​Consider the following hypothesis problem. n = 30
H0: σ2 = 500
S2 = 625
Ha: σ2 ≠ 500
​
At the 5% level of significance, the null hypothesis

Accepted Answer

A)  ​should be rejected. 
B)  ​should not be rejected. 
C)  ​should be revised. 
D)  should not be tested.

Question 9

Consider the following hypothesis problem. ​
N = 23
S2 = 60
H0: σ2 ≤ 66
Ha: σ2 > 66
​
If the test is to be performed at the .05 level of significance, the null hypothesis

Accepted Answer

A)  should be rejected. 
B)  should not be rejected. 
C)  should be revised. 
D)  should not be tested.

Question 10

A sample of 61 observations yielded a sample standard deviation of 6.If we want to test H0: σ2 = 40, the test statistic is

Accepted Answer

A)  54. 
B)  9.15. 
C)  54.90. 
D)  9.

Question 11

The contents of a sample of 26 cans of apple juice showed a standard deviation of .06 ounces.We are interested in testing whether the variance of the population is significantly more than .003.The null hypothesis is

Accepted Answer

A)  s2 > .003. 
B)  s2 ≤ .003. 
C)  σ2 > .003. 
D)  σ2 ≤ .003.

Question 12

The symbol used for the variance of the population is

Accepted Answer

A)  σ. 
B)  σ2. 
C)  s. 
D)  s2.

Question 13

The 95% confidence interval estimate of a population variance when a sample variance of 324 is obtained from a sample of 81 items is

Accepted Answer

A)  14.14 to 174.94. 
B)  243.086 to 453.520. 
C)  16.42 to 194.35. 
D)  254.419 to 429.203.

Question 14

A sample of 61 elements is selected to estimate a 95% confidence interval for the variance of the population.The chi-square values to be used for this interval estimation are

Accepted Answer

A)  40.482 and 83.298. 
B)  32.357 and 71.420. 
C)  34.764 and 67.505. 
D)  43.188 and 79.082.

Question 15

A sample of 21 elements is selected to estimate a 90% confidence interval for the variance of the population.The chi-square value(s) to be used for this interval estimation is(are)

Accepted Answer

A)  31.410. 
B)  12.443. 
C)  10.851 and 31.410. 
D)  12.443 and 28.412.

Question 16

Based on the sample evidence below, we want to test the hypothesis that population A has a larger variance than population B. ​
Sample A
Sample B
N
11
10
S2
12)1
5
​
The p-value is approximately

Accepted Answer

A)  .10. 
B)  .05. 
C)  .025. 
D)  .01.

Question 17

To avoid the problem of not having access to Tables of F distribution when F values are needed for the lower tail, the numerator of the test statistic for a two-tailed test should be the one with

Accepted Answer

A)  the larger sample size. 
B)  the smaller sample size. 
C)  the larger sample variance. 
D)  the smaller sample variance.

Question 18

To avoid the problem of not having access to tables of the F distribution when a one-tailed test is required and with F values given for the lower tail, let​ the

Accepted Answer

A)  smaller sample variance be the numerator of the test statistic. 
B)  larger sample variance be the numerator of the test statistic. 
C)  sample variance from the population with the smaller hypothesized variance be the numerator of the test statistic. 
D)  sample variance from the population with the larger hypothesized variance be the numerator of the test statistic.

Question 19

A random sample of 22 employees of a local utility firm showed that their monthly incomes had a sample standard deviation of $110.Provide a 90% confidence interval estimate for the standard deviation of the incomes of all employees of the firm.

Accepted Answer

The answer of A random sample of 22 employees of...

Question 20

The manager of the service department of a local car dealership has noted that the service times of a sample of 16 new automobiles has a standard deviation of 5 minutes.A 95% confidence interval estimate for the variance of service times for all their new automobiles is

Accepted Answer

A)  13.642 to 59.885. 
B)  9.46 to 34.09. 
C)  2.144 to 9.948. 
D)  2.728 to 11.977.

Exam 11: Inferences About Population Variances

The average score of a sample of 30 students on their second statistics examination was 85 with a standard deviation of 11.Is the variance of the population significantly more than 80? Use a .05 level of significance.

A sample of 22 bottles of soft drink showed a variance of .64 in their contents.At the 5% level, determine whether or not the standard deviation of the population is significantly different from .7 ounces.Use the critical value approach.

A sample of 30 items provided a sample mean of 28 and a sample standard deviation of 6.Test the following hypotheses using α = .05.What is your conclusion? H₀: σ² ≤ 25 H_a: σ² > 25

The sampling distribution used when making inferences about a single population's variance is

The symbol used for the variance of the sample is

A random sample of 20 observations showed a standard deviation of 8.At a .05 level of significance, test to see if the variance of the population is significantly less than 65.Use the critical value approach.

What is the 90% confidence interval estimate of a population standard deviation when a sample variance of 50 is obtained from a sample of 15 items?

Consider the following hypothesis problem. n = 30 H₀: σ² = 500 S² = 625 H_a: σ² ≠ 500 At the 5% level of significance, the null hypothesis

Consider the following hypothesis problem. N = 23 S² = 60 H₀: σ² ≤ 66 H_a: σ² > 66 If the test is to be performed at the .05 level of significance, the null hypothesis

A sample of 61 observations yielded a sample standard deviation of 6.If we want to test H₀: σ² = 40, the test statistic is

The contents of a sample of 26 cans of apple juice showed a standard deviation of .06 ounces.We are interested in testing whether the variance of the population is significantly more than .003.The null hypothesis is

The symbol used for the variance of the population is

The 95% confidence interval estimate of a population variance when a sample variance of 324 is obtained from a sample of 81 items is

A sample of 61 elements is selected to estimate a 95% confidence interval for the variance of the population.The chi-square values to be used for this interval estimation are

A sample of 21 elements is selected to estimate a 90% confidence interval for the variance of the population.The chi-square value(s) to be used for this interval estimation is(are)

Based on the sample evidence below, we want to test the hypothesis that population A has a larger variance than population B. Sample A Sample B N 11 10 S² 12) 1 5 The p-value is approximately

To avoid the problem of not having access to Tables of F distribution when F values are needed for the lower tail, the numerator of the test statistic for a two-tailed test should be the one with

To avoid the problem of not having access to tables of the F distribution when a one-tailed test is required and with F values given for the lower tail, let the

A random sample of 22 employees of a local utility firm showed that their monthly incomes had a sample standard deviation of $110.Provide a 90% confidence interval estimate for the standard deviation of the incomes of all employees of the firm.

The manager of the service department of a local car dealership has noted that the service times of a sample of 16 new automobiles has a standard deviation of 5 minutes.A 95% confidence interval estimate for the variance of service times for all their new automobiles is

Exam 11: Inferences About Population Variances

The average score of a sample of 30 students on their second statistics examination was 85 with a standard deviation of 11.Is the variance of the population significantly more than 80? Use a .05 level of significance.

A sample of 22 bottles of soft drink showed a variance of .64 in their contents.At the 5% level, determine whether or not the standard deviation of the population is significantly different from .7 ounces.Use the critical value approach.

A sample of 30 items provided a sample mean of 28 and a sample standard deviation of 6.Test the following hypotheses using α = .05.What is your conclusion? H0: σ2 ≤ 25 Ha: σ2 > 25

The sampling distribution used when making inferences about a single population's variance is

The symbol used for the variance of the sample is

A random sample of 20 observations showed a standard deviation of 8.At a .05 level of significance, test to see if the variance of the population is significantly less than 65.Use the critical value approach.

What is the 90% confidence interval estimate of a population standard deviation when a sample variance of 50 is obtained from a sample of 15 items?

​Consider the following hypothesis problem. n = 30 H0: σ2 = 500 S2 = 625 Ha: σ2 ≠ 500 ​ At the 5% level of significance, the null hypothesis

Consider the following hypothesis problem. ​ N = 23 S2 = 60 H0: σ2 ≤ 66 Ha: σ2 > 66 ​ If the test is to be performed at the .05 level of significance, the null hypothesis

A sample of 61 observations yielded a sample standard deviation of 6.If we want to test H0: σ2 = 40, the test statistic is

The contents of a sample of 26 cans of apple juice showed a standard deviation of .06 ounces.We are interested in testing whether the variance of the population is significantly more than .003.The null hypothesis is

The symbol used for the variance of the population is

The 95% confidence interval estimate of a population variance when a sample variance of 324 is obtained from a sample of 81 items is

A sample of 61 elements is selected to estimate a 95% confidence interval for the variance of the population.The chi-square values to be used for this interval estimation are

A sample of 21 elements is selected to estimate a 90% confidence interval for the variance of the population.The chi-square value(s) to be used for this interval estimation is(are)

Based on the sample evidence below, we want to test the hypothesis that population A has a larger variance than population B. ​ Sample A Sample B N 11 10 S2 12) 1 5 ​ The p-value is approximately

To avoid the problem of not having access to Tables of F distribution when F values are needed for the lower tail, the numerator of the test statistic for a two-tailed test should be the one with

To avoid the problem of not having access to tables of the F distribution when a one-tailed test is required and with F values given for the lower tail, let​ the

A random sample of 22 employees of a local utility firm showed that their monthly incomes had a sample standard deviation of $110.Provide a 90% confidence interval estimate for the standard deviation of the incomes of all employees of the firm.

The manager of the service department of a local car dealership has noted that the service times of a sample of 16 new automobiles has a standard deviation of 5 minutes.A 95% confidence interval estimate for the variance of service times for all their new automobiles is

A sample of 30 items provided a sample mean of 28 and a sample standard deviation of 6.Test the following hypotheses using α = .05.What is your conclusion? H₀: σ² ≤ 25 H_a: σ² > 25

Consider the following hypothesis problem. n = 30 H₀: σ² = 500 S² = 625 H_a: σ² ≠ 500 At the 5% level of significance, the null hypothesis

Consider the following hypothesis problem. N = 23 S² = 60 H₀: σ² ≤ 66 H_a: σ² > 66 If the test is to be performed at the .05 level of significance, the null hypothesis

A sample of 61 observations yielded a sample standard deviation of 6.If we want to test H₀: σ² = 40, the test statistic is

Based on the sample evidence below, we want to test the hypothesis that population A has a larger variance than population B. Sample A Sample B N 11 10 S² 12) 1 5 The p-value is approximately

To avoid the problem of not having access to tables of the F distribution when a one-tailed test is required and with F values given for the lower tail, let the