Refer to Problem 7.5. During the negotiations with the automobile ­manufacturer, Parnelli gets a sinking feeling that some of the cars he is thinking of purchasing for the forestry service might average less than 20 miles to the gallon of gasoline. According to the road test data, what percentage of the cars can be expected to fall below this mileage level? Should Parnelli be very worried?
Problem 7.5
Parnelli Jones, a vehicle manager for the northeast region of the forestry service, is charged with purchasing automobiles for service use. Because forestry service employees often have to drive long distances in isolated regions, Parnelli is very concerned about gasoline mileage for the vehicle fleet. One automobile manufacturer has told him that the particular model of vehicle that interests him has averaged 27.3 miles per gallon in road tests with a standard deviation of 3.1 ( normal distribution). Parnelli would like to be able to tell his superiors at the forestry service that the cars will get at least 25 miles to the gallon. According to the road test data, what percentage of the cars can be expected to meet this criterion? Parnelli also thinks that his superiors might settle for cars that got 24 miles to the gallon or better. What percentage of the cars can be expected to meet this criterion?