Question

1)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 38 months and a standard deviation of 10 months. Using the 68-95-99.7 rule, what is the approximate percentage of cars that remain in service between 48 and 68 months?

Do not enter the percent symbol.
ans = %

2)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 54 months and a standard deviation of 9 months. Using the empirical rule (as presented in the book), what is the approximate percentage of cars that remain in service between 63 and 81 months?

Do not enter the percent symbol.
ans = %

Answer 1

1) The distribution of the number of months in service for the fleet of cars is bell-shaped and has a mean of 38 months and a standard deviation of 10 months.

What is the approximate percentage of cars that remain in service between 48 and 68 months?

Here we want to use the 68-95-99.7 rule

Empirical Rule:

1) Approximate 68% of data falls within the 1 standard deviation from the mean.

2) Approximate 95% of data falls within the 2 standard deviation from the mean.

1) Approximate 99.7% of data falls within the 3 standard deviation from the mean.

Let's find the value of k

for x = 48

For x = 68

So that P(48 < X < 68) = P(1 < Z < 3)