A simple random sample of 60 items resulted in a sample mean of 71. The population standard deviation is 13.

a. Compute the 95% confidence interval for the population mean (to 1 decimal). ( , )

b. Assume that the same sample mean was obtained from a sample of 120 items. Provide a 95% confidence interval for the population mean (to 2 decimals). ( , )

c. What is the effect of a larger sample size on the margin of error?