Ratio, Proportion, And Percent Worksheet With Answers Page 3
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6Solving Two-Part Proportion Problems
For some word problems, you may have to use information in the problem to calculate one of
the terms before you can write a proportion.
Example:
David is helping children paint a mural. The pink color used in the mural is made
by mixing red and white paint in a 2:7 ratio. If David needs 36 quarts of pink paint, how many
quarts of red paint will he use?
David needs to know how much red paint is needed to mix with white to get 36 quarts of pink
paint. Set up a proportion using two ratios that compare the amount of red paint to the total
amount of paint (pink). Use the ratio you are given to find a total (pink). Add: 2 + 7 = 9.
There are 2 quarts of red paint in 9 quarts of pink. Write the other ratio comparing the unknown
x
amount of red to the total:
.
36
2
36
2 red
x red
=
= 8 red
Write the proportion and solve:
9
9 pink
36 pink
Answer: David will need 8 quarts of red paint.
36 = 72 and 9
8 = 72.
Check: Substitute and find the cross products: 2
S K I L L P R A C T I C E
Solve each problem.
1.
The distance from Kent to Leeds is 175 km. On a map with a scale of 1 cm = 25 km, how
many centimeters apart are Kent and Leeds?
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2.
The scale on a map of Oregon is 1 inch = 36 miles. Ontario and Burns are 5
inches apart
2
on the map. What is the actual distance between the cities?
3.
The ratio of children to adults on a camping trip is 5:2. If there are 56 people on the
camping trip, how many are children?
4.
Paul makes 1 sale in his shop for every 8 sales he makes over the telephone. If he averages
180 sales per week, how many are made in his shop?
S O C I A L S T U D I E S
C o n n e c t i o n
One strategy when solving a proportion problem on the GED test is to use labels.
Labels will help you to always keep the ratios in the same order.
Example:
In North Dakota, there are approximately 10 square miles of water for every
400 square miles of land. If the land area of North Dakota is nearly 69,000 square miles,
how many of the state’s square miles are water?
Write the labels in the order you want the numbers to appear. Then write the numbers.
water sq mi
10
x
=
=
land sq mi
400
69,000
Solve the proportion.
In North Dakota about how many square miles are covered
in water?
Answers and explanations start on page 315.
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