Question

The Department of Transportation (DOT) would like to test the hypothesis that the average age of cars on the road is less than 12 years. DOT took a random sample of 32 cars and test the hypothesis H 0: μ = 12 vs H a: μ < 12. The hypotheses test resulted in a test statistic of -1.93. Using a 5% level of significance, what is the appropriate conclusion?

a. Not enough information is provided.

b. There is sufficient evidence to conclude that the average age of cars on the road is less than 12 years.

c. There is not sufficient evidence to conclude that the average age of cars on the road is less than 12 years.

d. The sample size is not large enough to conduct the hypothesis test.

Answer 1

H 0: μ = 12 vs H a: μ < 12

Test Statistic(Z)=-1.93

It is one/left tailed test.

P-Value=P(Z<-1.93)

=0.0268 (use z table)

p-value is lesser than significance level(alpha=0.05), Reject the null Hypothesis.

Ans:

b. There is sufficient evidence to conclude that the average age of cars on the road is less than 12 years.