Question

The manufacturer of a new compact car claims the miles per gallon (mpg) for the gasoline consumption is mound-shaped and symmetric with a mean of 24.6 mpg and a standard deviation of 11.2 mpg. If 30 such cars are tested, what is the probability the average mpg achieved by these 30 cars will be greater than 27?

Answer 1

Use this "magic" page
http://davidmlane.com/hyperstat/z_table.html

enter the mean and sd as you have them
click on "above" and enter 27
you should get .4152

Answer 2

.0733