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 31.9 and 3.4 mpg, respectively.
a. If two passenger cars are randomly selected, what is the probability that all of the passenger cars get more than 34 mpg?
b. What is the probability that a randomly selected passenger car gets more than 34 mpg?