SOLUTION: Fast Service Truck Lines uses the Ford Super Duty F-750 exclusively. Management made a study of the maintenance costs and determined the number of miles travled during the year fol

Question 199119: Fast Service Truck Lines uses the Ford Super Duty F-750 exclusively. Management made a study of the maintenance costs and determined the number of miles travled during the year followed the normal distribution. The mean of the distribution was 60,000 miles and the standard deviation 2,000 miles.
a. What percent of the Ford Super Duty F-750's logged 65,200 miles or more?
b. What percent of the trucks logged more than 57,060 but less than 58,280?
c. What percent of the Fords travled 62,000 miles or less during the year?
d. Is it reasonable to conclude that any of the trucks were driven more than 70,000 miles? Explain
Answer by stanbon(75887) (Show Source): You can put this solution on YOUR website!
Fast Service Truck Lines uses the Ford Super Duty F-750 exclusively. Management made a study of the maintenance costs and determined the number of miles travled during the year followed the normal distribution. The mean of the distribution was 60,000 miles and the standard deviation 2,000 miles.
a. What percent of the Ford Super Duty F-750's logged 65,200 miles or more?
z(65200) = (65200-60000)/2000 = 5200/2000 = 2.6
P(x>=65200) = P(z>=2.6) = 0.00466
-----------------------
b. What percent of the trucks logged more than 57,060 but less than 58,280?
Find the z-values of each of these.
Then find the fraction of the population that lies between those z-values
I get 0.12411..
----------------------------
c. What percent of the Fords travled 62,000 miles or less during the year?
same procedure
I get: 0.8413...
-----------------------------------
d. Is it reasonable to conclude that any of the trucks were driven more than 70,000 miles? Explain
That figure is 5 standard deviations above the mean.
===========================================================
Cheers,
Stan H.

RELATED QUESTIONS
It is reported that 16 percent of American households use a cell phone exclusively for... (answered by stanbon)

They plan to have 10 bikes. Katie thinks they should charge �10 a day per bike. They... (answered by addingup)

It is reported that 24% of American households use a cell phone exclusively for their... (answered by Boreal)

It is reported that 16 percent of American households use a cell phone exclusively for... (answered by Boreal)

A manufacturer of automobile transmissions uses two different processes. Management... (answered by ElectricPavlov)

There were five customers service representative on duty at the electronic super store... (answered by ewatrrr)

A manufacturer of automobile transmissions uses three different processes. Management... (answered by greenestamps)

Super unleaded gasoline costs 9 cents more per gallon than regular unleaded gasoline. A... (answered by mananth)

Air Midwest is considering a new service between St. Louis and Orlando. It can use... (answered by macston)