Math Word Problems Demystified - A Self Teaching Guide

2

8

þ

3 : 6

8

þ

3 : 6

12

¼ 1

0 : 25 þ 0 : 45 þ 0 : 3 ¼ 1

1 ¼ 1

EXAMPLE:A swimming pool can be filled in 6 hours and drained in 15

hours. How long will it take to fill the pool if the owner has forgotten to close

the drain valve?

SOLUTION:

GOAL: You are being asked how long in hours it will take to fill the pool if

the drain is left open.

STRATEGY: Letx¼the time in hours it takes to fill the pool.

Rate  Time ¼Amount of work done

Fill pool^1

6

x^1

6

x

Empty pool^1

15

x^1

15

x

Since the drain is emptying the pool, the equation is

1

6

x

1

15

x¼ 1

IMPLEMENTATION: Solve the equation:

1

6

x

1

15

x¼ 1

The LCD is 30.

305

1



x

61

302

1



x

151

¼ 30  1

5 x
 2 x¼ 30

3 x¼ 30

186 LESSON 17 Solving Work Problems