Exam 9: One-Sample Hypothesis Tests

Dullco Manufacturing claims that its alkaline batteries last at least 40 hours on average in a certain type of portable CD player.But tests on a random sample of 18 batteries from a day's large production run showed a mean battery life of 37.8 hours with a standard deviation of 5.4 hours.To test DullCo's hypothesis,the test statistic is

Other things being equal,a large population standard deviation would weaken the power of a test for one mean.

A two-tailed hypothesis test for H0: μ = 15 at α = .10 is analogous to asking if a 90 percent confidence interval for μ contains 15.

The hypotheses H0: π ≥ .40,H1: π < .40 would require

If n = 25 and α = .05 in a right-tailed test of a mean with unknown σ,the critical value is

Which is not a likely reason to choose the z distribution for a hypothesis test of a mean?

In testing a proportion,normality of p can be assumed if nπ0 ≥ 10 and n(1 − π0)≥ 10.

For a given level of significance (α),increasing the sample size will increase the probability of Type II error because there are more ways to make an incorrect decision.

In a right-tailed test,the null hypothesis is rejected when the value of the test statistic exceeds the critical value.

For a given null hypothesis and level of significance,the critical value for a two-tailed test is greater than the critical value for a one-tailed test.

For a test of a mean,which of the following is incorrect?

Dullco Manufacturing claims that its alkaline batteries last at least 40 hours on average in a certain type of portable CD player.But tests on a random sample of 18 batteries from a day's large production run showed a mean battery life of 37.8 hours with a standard deviation of 5.4 hours.In a left-tailed test at α = .05,which is the most accurate statement?

In hypothesis testing,we are trying to prove the null hypothesis.

Which of the following is correct?

Which of the following statements is correct?

Which of the following is not a valid null hypothesis?

The probability of rejecting a false null hypothesis increases as the sample size increases,other things being equal.

In a left-tailed test,a statistician got a z test statistic of −1.720.What is the p-value?

The critical value in a hypothesis test

As you are crossing a field at the farm,your country cousin Jake assures you,"Don't worry about that old bull coming toward us.He's harmless." As you consider Jake's hypothesis,what would be Type I error on your part?