A company claims that 9 out of 10 doctors (i.e., 90%) recommend its brand of cough syrup to their patients. To test this claim against the alternative that the actual proportion is less than 90%, a random sample of doctors was taken. Suppose the test statistic is z = -2.23. Can we conclude that H0 should be rejected at the a) α = .10, b) α = .05, and c) α = .01 level?
A) a) yes; b) yes; c) no
B) a) yes; b) yes; c) yes
C) a) no; b) no; c) no
D) a) no; b) no; c) yes

Question

Quizplus · Accepted Answer

The critical z-value for a one-tailed test at α = 0.10 is -1.28, at α = 0.05 is -1.645, and at α = 0.01 is -2.33. Since -2.23 is less than -1.28 and -1.645, we reject H0 at α = 0.10 and α = 0.05, but not at α = 0.01.

A Company Claims That 9 Out of 10 Doctors (I