A car company says that the mean gas mileage for its luxury sedan is 21 mpg. You believe the mean gas mileage is lower than this and find that a random sample of 5 cars has a mean gas mileage of 19 mpg and a sample standard deviation of 4 mpg. Assume the gas mileage of all of the company’s luxury sedans is normally distributed. At α = 0.10, use a t-test to assert the validity of the company’s claim.
A critical value for this test is:
Question 20 options:
-1.533
1.533
1.28
-1.28