Question 18 (2 points) 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 & = 0.10, use a t-test to assert the validity of the company's claim. The alternative hypothesis is: HA: M 21 HA: M = 21 HA: M # 21