 # 8-3 Learn to use proportions to make conversions within the customary system.

```Proportions and Customary
8-3 Measurement
Learn to use proportions to make
conversions within the customary system.
Course 1
Proportions and Customary
8-3 Measurement
Course 1
Proportions and Customary
8-3 Measurement
cc
cc
cc
cc
Cup = 8 oz
cc
cc
Course 1
cc
cc
8-3 Dimensional Analysis
cup
cup
cup
cup
cup
cup
cup
cup
Course 2
Pint
Pint
Quart
Quart
Pint
Pint
Gallon
Pint
Pint
Quart
cup
cup
cup
cup
Quart
Pint
Pint
cup
cup
cup
cup
8-3 Dimensional Analysis
Course 2
8-3 Dimensional Analysis
12 inches = 1 foot
1 inch
Course 2
8-3 Dimensional Analysis
Course 2
8-3 Dimensional Analysis
Course 2
Proportions and Customary
8-3 Measurement
Additional Example 1A: Using Proportions to
Convert Measurements
A. Sonja went hiking for 4 hours. For how
many minutes did she go hiking?
1 hr
4 hr
_____
= ____
60 min
x min
60 • 4 = 1 • x
1 hour is 60 minutes. Write
a proportion. Use a
variable for the value you
are trying to find.
The cross products are equal.
240 = x
Sonja hiked for 240 minutes.
Course 1
Proportions and Customary
8-3 Measurement
Additional Example 1B: Using Proportions to
Convert Measurements
B. Mr. Lee is 72 inches tall. Find his height in feet.
1 foot is 12 inches. Write a
1 ft
x ft
____
____
proportion. Use a variable
=
12 in 72 in.
for the value you are trying
to find.
12 • x = 1 • 72 The cross products are equal.
12x = 72
x is multiplied by 12.
12x = ___
72
___
12
12
x=6
Divide both sides by 12 to undo
the multiplication.
Mr. Lee is 6 feet tall.
Course 1
Proportions and Customary
8-3 Measurement
Additional Example 1C: Using Proportions to
Convert Measurements
C. Hunter used 56 cups of water to wash his car.
How many gallons of water did he use?
1 gallon is 16 cups. Write a
1 gal
x gal
_______
______
=
16 cups
56 cups proportion. Use a variable for the
value you are trying to find.
16 • x = 1 • 56
The cross products are equal.
16x = 56
x is multiplied by 16.
16x = ___
56
___
16
16
x = 3.5
Divide both sides by 16 to undo
the multiplication.
Hunter used 3.5 gallons of water to wash his car.
Course 1
Proportions and Customary
8-3 Measurement
Try This: Example 1A
A. Helga went biking for 3 hours. For how
many minutes did she go biking?
1 hr
3 hr
_____
= ____
60 min
x min
60 • 3 = 1 • x
1 hour is 60 minutes. Write
a proportion. Use a
variable for the value you
are trying to find.
The cross products are equal.
180 = x
Helga biked for 180 minutes.
Course 1
Proportions and Customary
8-3 Measurement
Try This: Example 1B
B. Ms. Hagan is 60 inches tall. Find her height in
feet.
1 foot is 12 inches. Write a
1 ft
x ft
____
____
proportion. Use a variable
=
12 in. 60 in.
for the value you are trying
to find.
12 • x = 1 • 60
The cross products are equal.
12x = 60
x is multiplied by 12.
12x = ___
60
___
12
12
x=5
Divide both sides by 12 to undo
the multiplication.
Ms. Hagan is 5 feet tall.
Course 1
Proportions and Customary
8-3 Measurement
Try This: Example 1C
C. Seymour used 40 cups of water to wash his
dog. How many gallons of water did he
use?
1 gallon is 16 cups. Write a
1
gal
x
gal
_______ = ______
16 cups
40 cups proportion. Use a variable for the
value you are trying to find.
16 • x = 1 • 40
The cross products are equal.
16x = 40
x is multiplied by 16.
16x
40
___
= ___
16
16
x = 2.5
Divide both sides by 16 to undo
the multiplication.
Seymour used 2.5 gallons of water to wash his dog.
Course 1
Proportions and Customary
8-3 Measurement
Insert Lesson Title Here
Lesson Quiz
Find the missing value.
1.
in. = 6 yd
2. 24 pt =
gal
216
3
Compare. Write <, >, or =.
1 lb. >
2__
2
4. 7,920 ft 1.5 mi =
3. 42 oz
5. If your family is going to take a 3-week
vacation, how many days will you be gone?
21 days
Course 1
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