Question 1206710: 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 48 months and a standard deviation of 6 months. Using the 68-95-99.7 rule, what is the approximate percentage of cars that remain in service between 54 and 66 months?
Do not enter the percent symbol.
Answer by ikleyn(52863)   (Show Source):
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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 48 months and a standard deviation of 6 months.
Using the 68-95-99.7 rule, what is the approximate percentage of cars that remain in service between 54 and 66 months?
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Notice that in this problem 54 is one standard deviation from the mean of 48
and 66 is two standard deviations.
Since the normal distribution is symmetric, we may conclude that the percentage of cars
that remain in service between 54 and 66 months is half of (95-68)%, i.e. 13.5%. ANSWER
Solved.
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