Chapter 6, Problem 77P

You’re trying to decide whether to buy an energy-efficient 225-W refrigerator for $1150 or a standard 425-W model for $850. The standard model will run 20% of the time, but better insulation means the energy-efficient model will run 11% of the lime. If electricity costs 9.5¢/kW·h, how long would you have to own the energy-efficient model to make up the difference in cost? Neglect interest you might earn on your money.