Page 188 - Math Course 1 (Book 1)

Proportions

16 4.8
Solve the proportion = Examine
v 1.5
Check the cross products. Since 8 •55 = 440
and 22 • 20 = 440, the answer is correct.
16 4.8
=
v 1.5
16 • 1.5 = 4.8 • v Cross products Convert Measurements

24 = 4.8v Multiply.

24 4.8v Divide Example
=
4.8 4.8
5 = v ATTRACTIONS
The Circleville Pumpkin Show in Circleville, Ohio,
boasts the world’s largest pumpkin pie. The pie
weighs 350 pounds and is 5 feet in diameter.
Answer The solution is 5 Find the diameter of the pie in centimeters if 1
foot = 30.48 centimeters.

Let x represent the diameter in centimeters.
REAL WORLD EXAMPLE
customary customary
ARCHITECTURE Measurement measurement
An architect builds a model of a 1 ft = 5 ft
building before the actual building is metric 30.48 cm x cm
built. The model is 8 inches tall and Measurement metric
the actual building will be 22 feet tall. measurement
The model is 20 inches wide. Find the width of
the actual building. 1 • x = 30.48 • 5 Cross products
x = 152.4 Simplify.
Explore
You know the actual height of the building and
the corresponding height of the model. You need Answer The diameter of the pie is 152.4
to f nd the actual width of the building that corre- centimeters.
sponds with a model width of 20 inches.
Plan
Write and solve a proportion using ratios that Your Turn!
compare the actual building to the model. Let w
represent the actual width of the building. Solve Proportions
Solve x 3
Solve =
actual height actual width 12 8
= A. 32
model height model width B. 4
C. 4.5
22 w D. 36
= Write a proportion.
8 20
Answer
22 • 20 = 8 • w Cross products
5 3
440 = 8w Multiply. Solve =
m 4.2
440 8w
= Divide A. 7
8 8 B. 21
55 = w Simplify. C. 3.6
D. 30
The actual width of the building
Answer Answer
is 55 feet.

180