The highway fuel economy of a 2022 Acura RDX 2.0L 4-cylinder automatic 5-speed using premium fuel is a normally distributed random variable with a mean of = 19.50 mpg and a standard deviation of = 1.50 mpg. (a) What is the standard error of X, the mean from a random sample of 9 fill-ups by one driver? (Round your answer to 4 decimal places.) Standard error of X (b) Within what interval would you expect the sample mean to fall, with 95 percent probability? (Round your answers to 4 decimal places.) The interval is from to