Suppose that the miles-per-gallon (mpg) rating of passenger cars is a normally distributed random variable with a mean and a standard deviation of 33.8 and 3.5 mpg, respectively.
a. What is the probability that a randomly selected passenger car gets more than 35 mpg?
b. What is the probability that the average mpg of four randomly selected passenger cars is more than 35 mpg?
c. If four passenger cars are randomly selected, what is the probability that all of the passenger cars get more than 35 mpg?