posted by ggerrlo .
Suppose that the mpg rating of Passengers Cars is a normally distributed random variable with a mean and a standard deviation of 33,8 mpg and 3,5 mpg. Question : an automobiles manufacturer wants to build a new Passenger car with an mpg rating that improves upon 99% of existing Cars. What is the minimum mpg that would achieve this goal ?
Z = (score-mean)/SD
Find table in the back of your statistics text labeled something like "areas under normal distribution" to find the proportion/probability (.99) and its Z score. Insert data into above equation and solve for score.