a. In a random sample of 500 observations drawn from

a. In a random sample of 500 observations drawn from a normal population, the sample mean and sample standard deviation were calculated as x? = 350 and s = 100. Estimate the population mean with 99% confidence.,b. Repeat part (a) assuming that you know that the population standard deviation is ? = 100.,c. Explain why the interval Estimates were virtually identical.