Question

A company has a policy of retiring company cars; this policy looks at number of miles driven, purpose of trips, style of car and other features. The distribution of the number of months in service for the fleet of cars is bell-shaped and has a mean of 47 months and a standard deviation of 9 months. Using the 68-95-99.7 rule, what is the approximate percentage of cars that remain in service between 20 and 38 months?

Answer 1

The 68-95-99.7 rule

Mean = 47 months

Standard Deviation = 9 months

So 20 is and 38 is so we have to find the percentage from to

So percentage of cars = ( 99.73 - 68.27 ) / 2 divide by 2 because just one side

= 15.73%

Proportion will be 0.1573