Question

A mileage test is conducted for a new car model, the “Pizzazz.” Thirty (n=30) random selected Pizzazzes are driven for a month and the mileage is carefully measured in each. The mean mileage for the sample is 28.6 miles per gallon (mpg) and the sample standard deviation is 2.2 mpg. H0: µ = 27 H1: µ ≠ 27 What would have to happen in order for you to reject the null hypothesis? A. The test statistic would have to be smaller than the critical value. B. The test statistic would have to be larger than the critical value. C. The test statistic would have to be between the critical values. D. The test statistic would have to be less than the negative critical value or larger than the positive critical value.

Answer 1

H0: µ = 27
H1: µ ≠ 27

Xbar = 28.6
n = 30
sd = 2.2

critical value = t(a/2, n-1)
the null hypothesis is rejected when |t| > t(a/2,n-1) or p-value < alpha (5%)

B. The test statistic would have to be larger than the critical value.
D. The test statistic would have to be less than the negative critical value or larger than the positive critical value.