In a large city the distribution of incomes per family has a standard deviation of £2500.
For a random sample of 400 families, what is the probability that the sample mean per family is within £500 of the actual income per family?
In a large city the distribution of incomes per family has a standard deviation of £2500.
For a random sample of 400 families, what is the probability that the sample mean per family is within £500 of the actual income per family?