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