United Motors claims that one of its cars, the Starbird 300, gets city driving mileages that are normally distributed with a mean of 30 mpg and a standard deviation of l mpg. Let x denote the city driving mileage of a randomly selected Starbird 300.
a. Assuming that United Motors' claim is correct, find P(x ≤ 27).
b. If you purchase (randomly select) a Starbird 300 and your car gets 27 mpg in city driving, what do you think of United Motors' claim? Explain your answer.