Mileage ratings for cars and trucks generally come with a qualifier stating actual mileage will depend on driving conditions and habits. Ford states the Ecoboost F-150 3.5-L V6 will average 20 miles per gallon with combined town and country driving (source: www.

ford.com/trucks). Assume the mean stated by Ford is the actual average, and the distribution has a standard deviation of 3 mpg.

a. Given the above mean and standard deviation, what is the probability that 100 drivers will average more than 19.2 miles per gallon?

b. Suppose 1,000 drivers were randomly selected.

What is the probability the average obtained by these drivers will exceed 19.2 mpg?