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 63 months and a standard deviation of 8 months. Using the empirical rule (as presented in the book), what is the approximate percentage of cars that remain in service between 47 and 55 months?

Answer 1

Answer:

That probability is 0.1838 or 18.4%

Step-by-step explanation:

Answer 2

Answer:

That probability is 0.1838 or 18.4% or enter 18.4

Step-by-step explanation:

mean 35 sd 5

20 is 3 sd s to the left of the mean

30 is 1 sd to the left.

The empirical rule has 68% within 1 sd or 34% on one side

It has 95% within 2 sd or 47.5% on one side

It has 99.7% within 3 sd or 49.85% on one side

Therefore between 3 sd and 1 sd on one side is 49.85-34=15.85% or enter 15.9

mean of 48 sd 7

between 48 and 55 is between -1 and 0 sd or 34% enter 34. The last one doesn't seem to post easily:z=(x-mean)/sd or z< (1217-1481)/293 or z <-264/293 or -0.901,

That probability is 0.1838 or 18.4% or enter 18.4