SOLUTION: Here is the problem: Suppose you buy a new car whose advertised average mileage is 25 miles per gallon. After driving your car for several months, you find that its mileage is

Algebra ->  Absolute-value -> SOLUTION: Here is the problem: Suppose you buy a new car whose advertised average mileage is 25 miles per gallon. After driving your car for several months, you find that its mileage is       Log On


   

Question 36276: Here is the problem:
Suppose you buy a new car whose advertised average mileage is 25 miles per gallon. After driving your car for several months, you find that its mileage is 21.4 mpg. You phone the manufacturer and learn that the standard deviation of gas mileage for all cars of the model you bought is 1.15 mpg. Does it appear that your car is getting unusually low gas mileage? Explain your reasoning.
Thanks!
Answer by stanbon(75887) About Me  (Show Source):
You can put this solution on YOUR website!
Convert your milage of 21.4 into a "z" score as follows:
(21.4-25)/1.15 = -3.13
This means the gas milage you are getting is more than
three standard deviations below the advertised average.
This is a statistically significant difference and you
should be concerned.
Cheers,
Stan H.