In the EAi sampling problem, the population mean is $51,700 and the population standard deviation is $4,000. When the sample size is n=30, there is a 0.5034 probability of obtaining a sample mean within 8500 of the population mean. Use z-table, a. What is the probability that the sample mean is within $500 of the population mean if a sample of size 60 is used (to 4 decimals)? b. What is the probability that the sample mean is within $500 of the population mean if a sample of size 120 is used (to 4 decimals)