The city housing department wants to estimate the average re

The city housing department wants to estimate the average rent for rent-controlled apartments. They need to determine the number of renters to include in the survey in order to estimate the average rent to within ± $60 using a 95% confidence interval of the mean.

If = $250, how many renters are needed in the survey to meet the requirements?

Solution

95% confidence interval for population mean (Mu) is
sample mean +/- margin of error
Margin of error = z-score for confidence level*standard deviation/sqrt sample size
60 = 1.96*250/sqrt n
sqrt n = 1.96*250/60
n = (1.96*250/60)^2 = 67
Required number of renters in the survey = 67