The highway fuel economy of a 2016 Lexus RX FWD 6-cylinder 3.5 L automatic 5-speed using premium fuel is a normally distributed random variable with a mean of = 21.00mpg and a standard deviation of = 3.25mpg

a) What is the standard error of , the mean from a random sample of 16 fill-ups by one driver? (round to 4 decimal places)

Standard error of ______________________

b) Within what interval would you expect the sample mean to fall with, 90% probability? (round to 4 decimal places)

The interval is from_______________________ to _______________________