Exam 11: Inferences About Population Variances

We are interested in testing to see if the variance of a population is less than 7.The correct null hypothesis is

Consider the following hypothesis problem. ​ N = 23 S² = 60 H₀: σ² ≤ 66 H_a: σ² > 66 ​ The p-value is

A large company has claimed that the standard deviation of the monthly incomes of their employees is less than or equal to $120.To test their claim, a random sample of 76 employees of the company was taken; and it was determined that the standard deviation of their incomes was $135.Using α = .10, test the company's claim.

A sample of 28 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​

​Consider the following hypothesis problem. n = 30 H₀: σ² = 500 S² = 625 H_a: σ² ≠ 500 ​ ​The null hypothesis is to be tested at the 5% level of significance.The critical value(s) from the chi-square distribution table is(are)

There is a .90 probability of obtaining a value such that ​

The sampling distribution of the quantity (n - 1)s²/σ² is the

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 test statistic is

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 5% level, the critical value(s) from the chi-square distribution table is(are)

A sample of 61 items provided a sample mean of 932, a sample mode of 900, and a sample standard deviation of 11.Test the following hypotheses using α = .05.What is your conclusion? H₀: σ² ≤ 80 H_a: σ² > 80

The producer of a certain medicine claims that their bottling equipment is very accurate and that the standard deviation of all their filled bottles is .2 ounces or less.A sample of 20 bottles showed a standard deviation of .12 ounces.The test statistic to test the claim is

A sample of 16 students showed that the variance in the number of hours they spend studying is 25.At the 5% level of significance, test to see if the variance of the population is significantly different from 30.Use the critical value approach.

For a sample size of 21 at 95% confidence, the chi-square values needed for interval estimation are

Consider the following hypothesis problem. n = 23 S² = 60 H₀: σ² ≤ 66 H_a: σ² > 66 ​ The test statistic has a value of

The critical value of F using α = .05 when there is a sample size of 21 for the sample with the smaller variance, and there is a sample size of 9 for the sample with the larger sample variance is

​Consider the following sample information from Population A and Population B. ​ ​ Sample A Sample B N 24 16 S² 32 38 ​​ We want to test the hypothesis that the population variances are equal.The null hypothesis is to be tested at the 10% level of significance.The critical value from the F distribution table is

We are interested in determining whether or not the variances of the starting salaries of accounting majors is significantly different from management majors.The following information was gathered from two samples. Accounting Management Sample Size 21 18 Average Monthly Income $3600 $3500 Variance $900 $400 ​ At the .1 level of significance, test to determine whether or not the variances are equal.

A random sample of 41 scores of students taking the ACT test showed a standard deviation of 8 points.Provide a 98% confidence interval estimate for the standard deviation of all the ACT test scores.

The manager of the service department of a local car dealership has noted that the service times of a sample of 30 new automobiles has a standard deviation of 5 minutes.A 95% confidence interval estimate for the standard deviation of the service times (in minutes) for all their new automobiles is

The 99% confidence interval estimate for a population variance when a sample standard deviation of 12 is obtained from a sample of 10 items is