The Department of Transportation would like to test the hypothesis that the average age of cars on the road is less than 12 years. A random sample of 45 cars had an average age of 10.6 years. It is believed that the population standard deviation for the age of cars is 4.1 years. The Department of Transportation would like to set α = 0.05. The critical value for this hypothesis test would be ______.
A)2.575
B)1.28
C)1.645
D)1.96

Question

Quizplus · Accepted Answer

Given that the Department of Transportation is conducting a one-tailed test (since they are testing if the average age is less than 12 years) with a significance level of α = 0.05, the critical value corresponds to the z-score that cuts off the lower 5% of the normal distribution. The correct z-score for a one-tailed test with α = 0.05 is 1.645.

The Department of Transportation Would Like to Test the Hypothesis