Last year, KAAA's share of the 6 pm news audience was approximately equal to, but not greater than, 25 percent. This station's advertising department believes the current audience share is higher than last year's 25 percent share. In an attempt to substantiate this belief, the station surveyed a random sample of 400 6 pm viewers and found that 146 watched KAAA.
-The rejection point for testing these hypotheses at α = .001 is _____.
A)3.09
B)2.575
C)2.33
D)1.96
E)3.00

Question

Quizplus · Accepted Answer

The rejection point for testing these hypotheses at α = .001 corresponds to the z-score in a standard normal distribution that has a cumulative probability of 1 - α/2 (for a two-tailed test) or 1 - α (for a one-tailed test). Since the advertising department believes the current audience share is higher, this suggests a one-tailed test. For α = .001, the z-score that corresponds to the upper tail of the standard normal distribution is approximately 3.09. This value is used to decide whether to reject the null hypothesis in favor of the alternative hypothesis that the current audience share is higher than last year's 25 percent share.

Last Year, KAAA's Share of the 6 Pm News Audience