Question

a. 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 45 months and a standard deviation of 3 months. Using the empirical rule (as presented in the book), what is the approximate percentage of cars that remain in service between 48 and 51 months?b. The physical plant at the main campus of a large state university recieves daily requests to replace fluorescent lightbulbs. The distribution of the number of daily requests is bell-shaped and has a mean of 64 and a standard deviation of 7. Using the empirical rule (as presented in the book), what is the approximate percentage of lightbulb replacement requests numbering between 57 and 64?

Answer 1

In this case

`\begin{gathered} 48=45+3 \\ 51=45+2(3) \end{gathered}`

Therefore, the percentage that lies between 45 and 48 is given by

`(68)/(2)=34\text{ \%}`

And, the percentage that lies between 45 and 51 is given by

`(68)/(2)=34\text{ \%}`