ATM machines have made it easier and faster for customers to check account balances, transfer money, and obtain cash. Many banks are now considering the next generation of ATM machines, which will...

ATM machines have made it easier and faster for customers to check account balances, transfer money, and obtain cash. Many banks are now considering the next generation of ATM machines, which will feature news headlines, full-motion video, and tickets to events. In a random sample of 500 customers, 280 said ATM machines should offer postage stamps.

a. Find the sample proportion of customers who believe ATM machines should offer postage stamps, and check the nonskewness criterion.

b. Find a 99% confidence interval for the true proportion of customers who believe ATM machines should offer postage stamps.

c. A bank official claims the proportion of customers who believe ATM machines should offer postage stamps is 0.60. Is there any evidence to refute this claim?

A 0.2-kiloton “bunker buster” missile is designed to destroy enemy bunkers approximately 70 feet deep. To prevent fallout, the missile must penetrate 120 feet below the ground. In tests conducted by the military, eight missiles were fired and the penetration depth (in feet) of each was recorded. The data are given in the table below.