Exam 11: Inferences About Population Variances

A sample of 60 items from population 1 has a sample variance of 8, while a sample of 40 items from population 2 has a sample variance of 10. If we test whether the variances of the two populations are equal, the test statistic will have a value of _____.

The bottler of a certain soft drink claims its equipment to be accurate and that the variance of all filled bottles is .05 or less. The null hypothesis in a test to confirm the claim would be written as _____.

In a hypothesis test about two population variances, the test statistic F is computed as _____.

A sample of n observations is taken from a population. When performing statistical inference about a population variance, the appropriate χ² distribution has _____.

Test scores of two independent samples of students from UA and UB on a national examination are given below. At a .05 level of significance, test to determine if there is a significant difference between the variances of the two populations. UA UB 82 70 90 80 65 60 83 90 80 75

Two classes in business statistics showed the following results on a recent test. Class 1 Class 2 Sample size 25 21 Sample mean 82 84 Sample standard deviation 6.2 7.6 Carry out a test to determine whether the difference in the variance of the scores on this test is due to chance variation or is statistically significant with a .02 level of significance.

The χ² value for a one-tailed (upper tail) hypothesis test at 95% confidence and a sample size of 25 is _____.

The standard deviation of the daily temperatures in Honolulu last year was 3.2 degrees Fahrenheit. A random sample of 19 days resulted in a standard deviation of 4 degrees Fahrenheit. Has there been a significant change in the variance of the temperatures? Use α = .02.

There is a .90 probability of obtaining a ?² value such that _____.

The symbol used for the variance of the population is _____.

We are interested in determining whether or not the variances of the starting salaries of accounting majors are significantly different from the starting salaries of management majors. The following information was gathered from two samples: Accounting Management Sample size 16 16 Average monthly income \ 2,400 \ 2,500 Standard deviation \ 105 \ 125 At a 5% level of significance, test to determine whether or not the variances are equal. ​

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

The 95% confidence interval estimate for a population variance when a sample variance of 30 is obtained from a sample of 12 items is _____.

The random variable for a chi-square distribution may assume any _____.

In practice, the most frequently encountered hypothesis test about a population variance is a _____.

The sampling distribution used when making inferences about a single population's variance is a(n) _____ distribution.

The value of F_0.01 with 9 numerator and 20 denominator degrees of freedom is _____.

Which of the following rejection rules is proper?

The χ² values (for interval estimation) for a sample size of 10 at 95% confidence are _____.

The producer of a certain medicine claims that its bottling equipment is very accurate and that the standard deviation of all its filled bottles is 0.1 ounce or less. A sample of 20 bottles showed a standard deviation of .11. The test statistic to test the claim is _____.