A survey claims that 9 out of 10 doctors recommend aspirin for their patients with headaches. To test this claim against the alternative that the actual proportion of doctors who recommend aspirin is less than 0.90, a random sample of 100 doctors was selected. Suppose that the test statistic is -2.20. Can you conclude that H₀ should be rejected at the (a) α = 0.10, ?(b) α = 0.05, and (c) α = 0.01 level of Type I error?
A) (a) yes; (b) yes; (c) yes
B) (a) no; (b) no; (c) no
C) (a) no; (b) no; (c) yes
D) (a) yes; (b) yes; (c) no

Question

Quizplus · Accepted Answer

We need to calculate the p-value for the test statistic -2.20. Since this is a one-tailed test (less than alternative), we look up the area to the left of -2.20 in the t-distribution with 99 degrees of freedom. We get a p-value of 0.0161.

(a) Since α = 0.10 and p-value < α, we reject H₀. 
(b) Since α = 0.05 and p-value < α, we reject H₀. 
(c) Since α = 0.01 and p-value < α, we reject H₀.

Therefore, the correct answer is D.

A Survey Claims That 9 Out of 10 Doctors Recommend