An iq test is designed so that the mean is 100 and the standard deviation is 21 for the population of normal adults. Find the sample size necessary to estimate the mean IQ scores of statistics...

An iq test is designed so that the mean is 100 and the standard deviation is 21 for the population of normal adults. Find the sample size necessary to estimate the mean IQ scores of statistics students such that it can be said with 95% confidence that the sample mean is within 4 IQ points of the true mean. Assume that the population standard deviation is 21 and determine the required sample size using technology. Then determined if this is a reasonable sample size for a real world calculation.