HW #18: Testing Means

A SRS of 18 statistics examinations was taken from a large normal population. The average score in the sample was 76.6 with a sample variance (not sample standard deviation) of 51.84. We are interested in determining whether the average grade of the population is significantly different from 70. The p-value for this test is

0.00118

The average income in a certain area is assumed to be approximately $35,000. Assume the standard deviation of the incomes in the area to be $8,000. We wish to test if the average income in the area is less than $35,000. A SRS of size 36 yields a sample mean of $37,000. Compute the appropriate p-value for the test.

0.9332

The average income in a certain area is assumed to be approximately $35,000. Assume the standard deviation of the incomes in the area to be $8,000. We wish to test if the average income in the area is less than $35,000. A SRS of size 36 yields a sample mean of $37,000. What is the value of the test statistic for this problem?

1.5

A SRS of 18 statistics examinations was taken from a large normal population. The average score in the sample was 76.6 with a sample variance (not sample standard deviation) of 51.84. We are interested in determining whether the average grade of the population is significantly different from 70. How many degrees of freedom are associated with the t-distribution for this test?

17

A SRS of 18 statistics examinations was taken from a large normal population. The average score in the sample was 76.6 with a sample variance (not sample standard deviation) of 51.84. We are interested in determining whether the average grade of the population is significantly different from 70. What is the value of the test statistic for this problem (note that σ is unknown)?

3.889

The average income in a certain area is assumed to be approximately $35,000. Assume the standard deviation of the incomes in the area to be $8,000. We wish to test if the average income in the area is less than $35,000. A SRS of size 36 yields a sample mean of $37,000. State the appropriate set of hypotheses to test whether the average income of this area is as assumed.

Ho: μ = $35,000 vs Ha: μ < $35,000

A SRS of 18 statistics examinations was taken from a large normal population. The average score in the sample was 76.6 with a sample variance (not sample standard deviation) of 51.84. We are interested in determining whether the average grade of the population is significantly different from 70. The correct set of hypotheses is

Ho: μ = 70 vs Ha: μ ≠ 70

A computer magazine is evaluating the charge life of a new notebook computer battery. As part of its investigation, it tests the following hypotheses. H0: The mean charge life is 7 hours. Ha: The mean charge life is more than 7 hours. Which of the following decisions would result in committing a type II error?

None of the other answers are Type II errors

The average income in a certain area is assumed to be approximately $35,000. Assume the standard deviation of the incomes in the area to be $8,000. We wish to test if the average income in the area is less than $35,000. A SRS of size 36 yields a sample mean of $37,000. What is the conclusion, and why?

accept (fail to reject) Ho, p-value > 0.05

A SRS of 18 statistics examinations was taken from a large normal population. The average score in the sample was 76.6 with a sample variance (not sample standard deviation) of 51.84. We are interested in determining whether the average grade of the population is significantly different from 70. It can thus be concluded that the average grade of the population is You Answered

significantly different than 70