A marketing company wants to know the mean price of new vehiclessold in an up-and‑coming area of town. Marketing strategists takesa simple random sample of 756 cars, and find that the sample has amean of $27,400 and a standard deviation of $1300.
1. Assume that the population standard deviation is unknown.What is the error of estimate for a 95% confidence interval?
2. Assume that the population standard deviation is known to be$1500. What is the upper bound for a 98% confidence interval?
3. Assume that the population standard deviation is known to be$1500. Find the error of estimate for a 99% confidenceinterval.
4. Assume that the population standard deviation is known. Ifthe marketing strategists want the 90% confidence interval to bewithin $50 of the population mean, how many cars at minimum shouldthey sample?
