Pre-Algebra Demystified

EXAMPLE

How many cubic yards of dirt must be removed from a rectangular found-

ation for a house that measures 54 feet by 28 feet by 8 feet?

SOLUTION

Find the volume of the rectangular solid:

V¼lwh

¼54 ft28 ft8ft

¼ 12 ;096 ft^3

Since the problem asks for cubic yards, change 12,096 cubic feet to cubic

yards:

12,096 27 ¼448 yd^3

PRACTICE

1. A silo is 32 feet high and has a diameter of 10 feet. How many cubic
   feet will it hold? Usep¼3.14.


2. If a rug sells for $35 a square yard, how much will it cost to cover the
   floor of a room that measures 12 feet by 15 feet?


3. If a revolving lawn sprinkler will spray a distance of 12 feet, how many
   square feet will the sprinkler cover in one revolution? Usep¼3.14.


4. How many cubic yards of air would be in a balloon that has a 30 foot
   diameter? Usep¼3.14.


5. How many decorative bricks 10 inches long would be needed to go
   around a circular garden that is 8 feet in diameter? Usep¼3.14.

ANSWERS

1. 2512 ft^3


2. $700


3. 452.16 ft^2


4. 523.33 yd^3 (rounded)


5. About 30

Square Roots

In Chapter 2 you learned how to square a number. For example, 7^2 ¼ 7  7

¼49 and 3^2 ¼ 3  3 ¼9. The opposite of squaring a number is taking the

182 CHAPTER 9 Informal Geometry