Math Word Problems Demystified - A Self Teaching Guide

SOLUTION:

GOAL: You are being asked to determine how far the plane can travel in 5
hours.

STRATEGY: Write the ratio: The ratio statement is 360 miles to 3 hours or

360 miles

3 hours

¼

xmiles

5 hours

IMPLEMENTATION: Solve the proportion.

360 miles

3 hours

¼

xmiles

5 hours

3 x¼ 360  5

3 x¼ 1800

31 x

31

¼

1800

3

x¼600 miles

The plane can fly 600 miles.

EVALUATION:

360

3

¼

600

5

Substitute the value forxin the proportion

3  600 ¼ 5  360 and cross-multiply. If the cross products

1800 ¼ 1800 are equal, the answer is correct.

Notice that when you set up a proportion, always place the same units in
the numerator and the same units in the denominator. In the previous
problem,mileshours¼hoursmiles.

LESSON 6 Using Proportions 53