4. The R and D unit at a major auto-makers sampled 36 of the new Model JZ-5 sport cars. They ran each car for one hour on a test track. For the 36 cars the
mean mpg (miles per gallon) was x = 47.8 with a standard deviation of 4.8 mpg.
a. Construct a 98% confidence interval for the mean mpg for the entire year's production of the Model JZ-5.
b. State the meaning of the interval in the context of the problem.
