Page 425 - Basic College Mathematics with Early Integers

402 C HAPTE R 5 I RATIO, PROPORTION, AND MEASUREMENT

Objective Performing Operations on U.S. System
Units of Weight

Performing arithmetic operations on units of weight works the same way as
performing arithmetic operations on units of length.

PRACTICE 4 Example 4 Subtract 3 tons 1350 lb from 8 tons 1000 lb.
Subtract 5 tons 1200 lb from
8 tons 100 lb. Solution: To subtract, we line up similar units.
8 tons 1000 lb
- 3 tons 1350 lb

Since we cannot subtract 1350 lb from 1000 lb, we borrow 1 ton from the 8 tons.To
do so, we write 1 ton as 2000 lb and combine it with the 1000 lb.

7 tons+ 1 ton 2000 lb
8 tons 1000 lb = 7 tons 3000 lb
– 3 tons 1350 lb = – 3 tons 1350 lb
4 tons 1650 lb
To check, see that the sum of 4 tons 1650 lb and 3 tons 1350 lb is 8 tons 1000 lb.

Work Practice 4

PRACTICE 5 Example 5 Divide 9 lb 6 oz by 2.
Divide 5 lb 8 oz by 4.
Solution: We divide each of the units by 2.

4 lb 11 oz
2 9 lb 6 oz
-8
1 lb = 16 oz
22 oz Divide 2 into 22 oz to get 11 oz.
To check, multiply 4 pounds 11 ounces by 2.The result is 9 pounds 6 ounces.

Work Practice 5

PRACTICE 6 Example 6 Finding the Weight of a Child
A 5-lb 14-oz batch of cookies is
packed into a 6-oz container Bryan weighed 8 lb 8 oz at birth. By the time he was 1 year old, he had gained 11 lb
before it is mailed. Find the 14 oz. Find his weight at age 1 year.
total weight. Solution:

birth weight : 8 lb 8 oz
+ weight gained : + 11 lb 14 oz
total weight : 19 lb 22 oz

Since 22 oz equals 1 lb 6 oz,

19 lb 22 oz=19 lb+1 lb 6 oz
=20 lb 6 oz Copyright 2012 Pearson Education, Inc.
Bryan weighed 20 lb 6 oz on his first birthday.
Answers
4. 2 tons 900 lb 5. 1 lb 6 oz Work Practice 6
6. 6 lb 4 oz