Please review and confirm that my answers are correct (9)

A car company says that the mean gas mileage for its luxury sedan is at least 24

miles per gallon(mpg). You believe the claim is incorrect and find that a random sample of 7 cars has a mean gas mileage of 21 mpg and a standard deviation of 3

mpg. At =0.10, test thecompany's claim. Assume the population is normally distributed.

Which sampling distribution should be used andwhy?

A:

Use at-sampling distribution because the population isnormal, and sigma

is unknown.

What is the value of the standardized teststatistic?

A:

The standardized test statistic is 2.65

What is the criticalvalue?

A:

The critical value is

1.943

What is the outcome and the conclusion of thistest?

A:

Reject H0. At the 10% significancelevel, there is sufficient evidence to reject the carcompany's claim that the mean gas mileage for the luxury sedan is at least 24 miles per gallon.