A Grocery Store Manager Must Decide Whether to Buy Four

Multiple Choice

A grocery store manager must decide whether to buy four carpet-cleaning machines so that the store can rent them to customers.The manager estimates that the first machine would yield an income of $200 per year, the second $150, the third $75, and the fourth $20.Suppose the interest rate is 12 percent and each machine costs $500.How many carpet-cleaning machines should the manager buy?  

A)  none 
B)  one 
C)  two 
D)  three