{Exercise 7.19}

In the EAI sampling problem, the population mean is $51,200 and the population standard deviation is $5,000. When the sample size isn= 20, there is a 0.3472 probability of obtaining a sample mean within +/- $500 of the population mean.

1. What is the probability that the sample mean is within $500 of the population mean if a sample of size 40 is used (to 4 decimals)?
2. What is the probability that the sample mean is within $500 of the population mean if a sample of size 80 is used (to 4 decimals)?