An advertising agency wants to estimate the mean income of families located in a particular 50-block area of a low-income section of Chicago.
There are 10,000 families in the whole area, and the agency chooses a random sample of 100.
The mean income of these (100) families is $18,000 per year.
a. Compute a 95% confidence interval for the population mean, if the population standard deviation is known to $5,000.
b. If there were 20,000 families (rather than 10,000 families) in this area, would your answer to part (a) be altered?