The owner of a large fleet of taxis is trying to estimate the average
consumption of gasoline. Assume that the consumption has a normal
distribution. A random sample of 10 taxis is taken. The sample
indicates that an average value of the miles per gallon is 31 and a
sample standard deviation of 28.6 miles per gallon.
(1)	 What is the point estimate of the average miles per gallon of all
taxis in his fleet.
(2)at 90% confidence, what is the margin of error?
(3)develop a 90% confidence interval estimate of the average miles per
gallon of all taxis in his fleet