Question

Joni usually buys 20 pounds of dog food at the pet store for $19.95. She gets a coupon in the mail for 15% off a 10 pound bag, normally priced at $12.95. Which is cheaper per pound?

Answer 1

19.95

Explanation:

This is one of those questions that are a must do. The process is called estimation and if you follow it carefully, you learn a lot.

Round 19.95 to 20

Round 12.95 to 13 dollars. You get 15% off. which is about (1.50 + 0.75 = 2.25)

This the 10 pound bag down to 13 - 2.25 = 10.75. This is higher than 1 dollar per pound.

20 pounds for 20 dollars = 1 dollar per pound.