Question

The maker of a certain model car claimed that the car averaged at least 36 miles per gallon of gasoline. A sample of nine cars was selected and each car was driven with one gallon of regular gasoline. The sample showed a mean of 34.43 miles with a standard deviation of 3 miles. Assume you doubt that the car can achieve 36 miles per gallon - you believe the fuel efficiency would actually be lower. State your hypothesis and test your hypothesis.

Answer 1

H0: $\mu$ = 36

Ha: $\mu$ < 36

Test statistics

t = ($\bar{x}$ - $\mu$ ) / ( S / sqrt(n) )

= ( 34.43 - 36) / ( 3 / sqrt(9) )

= -1.57

This is test statistics value.

Critical value at 0.05 level with 8 df = -1.860

Since test statistics t > -1.860, Do not reject H0.