In the EAI sampling problem, the population mean is $71,500 and the population standard deviation is $5000. For n = 20, there is a 0.4108 probability of obtaining a sample mean within +$600 of the population mean. Use z-table. a. What is the probability that is within $600 of the population mean if a sample of size 40 is used (to 4 decimals)? b. Answer part (a) for a sample of size 80 (to 4 decimals).