Math Word Problems Demystified - A Self Teaching Guide

Hence, if both work together, then they can cut the lawn in 1.2 hours.

EVALUATION: Check the equation:

x¼ 1 : 2

1 : 2

2

þ

1 : 2

3

¼ 1

0 : 6 þ 0 : 4 ¼ 1

1 ¼ 1

EXAMPLE:One pipe can fill a large tank in 5 hours and a smaller pipe can
fill the same tank in 3 hours. How long will it take both pipes to fill the tank
if they are turned on at the same time?

SOLUTION:

GOAL: You are being asked to find the time in hours it would take to fill the
tank if both pipes are filling the tank at the same time.

STRATEGY: Letx¼the time it takes to fill the tank with both pipes. In one
hour, the first pipe does^15 of the work and the second pipe does^13 of the work.

Rate  Time ¼ Amount of work done

First pipe^1

5

x^1

5

x

Second pipe^1

3

x^1

3

x

Again, the total amount of work done is 100% or 1.

The equation is

x

5

þ

x

3

¼ 1

IMPLEMENTATION: Solve the equation:

x

5

þ

x

3

¼ 1

LESSON 17 Solving Work Problems 183