Question: Phone bills for residents of a certain city have a mean of $64 and a standard deviation of $9. Random samples of 36 phone bills are drawn from this population, and the mean of each sample is determined.

a. What is the mean of the sampling distribution of the sample mean?

a. What is the standard deviation of the sampling distribution of the sample mean?

a. Below are two probability density curves, one of which is the distribution of the phone bills in this city and the other is the sampling distribution for the sample mean. Which probability density curve is the sampling distribution? Briefly explain your choice.