A survey of 42 randomly selected "IPhone" owners showed that the purchase price has a mean of $408 with a sample standard deviation of $170. a. Compute the standard error of the sample mean. (Round the final answer to the nearest whole number.) Standard error b. Compute the 95% confidence Interval for the mean. (Round the final answers to 2 decimal places.) The confidence Interval is between $ and $ c. How large a sample is needed to estimate the population mean within $5 at a 95% degree of confidence? (Round the final answer to the nearest whole number.) Sample size