The manufacturer of a new compact car claims the distribution of miles per gallon (mpg) for the gasoline consumption is mound shaped and symmetrical with mean

25.9 mpg and standard deviation 9.5 mpg. If 30 such cars are tested, what it the

probability the average mpg x-bar (sorry, equation editor doesn't work any more) is

9. less than 23 mpg?

10. greater than 28 mpg?

11. between 23 and 28 mpg?