6.4 Notes
December 19, 2011
6.4 Percent of a Number
Warm Up
Multiply.
1. 0.05
*
20 =
2. 0.32
*
15 =
3. 0.06
*
25 =
4. 0.75
*
18 =
5. 0.34
*
76 =
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6.4 Notes
December 19, 2011
Problem of the Day
In a group of 60 triangular and square
tiles, 25% are red, and 75% are blue. The
ratio of triangles to squares is 1:2.
Seventy percent of the squares are blue.
Find the number of each kind of tile (red
or blue squares or triangles).
3 red triangles
17 blue triangles
12 red squares
28 blue squares
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6.4 Notes
December 19, 2011
6.4 Percent of a Number
Learn to find the percent of a number.
The human body is made up mostly of water. In fact,
about 67% of a person’s total (100%) body weight is
water. If Cameron weighs 90 pounds, about how
much of his weight is water?
Remember that a percent is a part of 100. Since you
want to know the part of Cameron’s body that is water,
you can set up and solve a proportion to find the
answer.
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6.4 Notes
December 19, 2011
Example 1A: Using Proportions to Find Percents of Numbers
Find the percent of each number.
30% of 50
Convert percent to a decimal.
Multiply.
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6.4 Notes
December 19, 2011
Example 1B: Using Proportions to Find Percents of Numbers
Find the percent of each number.
200% of 24
Convert percent to a decimal.
Multiply.
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6.4 Notes
December 19, 2011
Check It Out: Example 1A
Find the percent of each number.
40% of 40
Convert percent to a decimal.
Multiply.
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6.4 Notes
December 19, 2011
Check It Out: Example 1B
Find the percent of each number.
150% of 64
Convert percent to a decimal.
Multiply.
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6.4 Notes
December 19, 2011
Check It Out: Additional Practice
21% of 40
3% of 12
9% of 80
6% of 18
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6.4 Notes
December 19, 2011
Additional Example 3: Geography Application
The estimated world population in 2001
was 6,157 million. About 40% of the people
were 19 or younger. What was the
approximate number of people 19 or
younger, to the nearest million?
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6.4 Notes
December 19, 2011
Check It Out: Example 3
The estimated world population in 2001
was 6,157 million. About 60% of the people
were above 19 years of age. What was the
approximate number of people 19 or older,
to the nearest million?
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6.4 Notes
December 19, 2011
Lesson Quiz
Find the percent of each number.
1. 25% of 8
2. 40% of 110
3. 150% of 96
4. 0.3% of 120
5. Williams Middle School has 850 students. If 42%
of the students bought lunch on Monday, how
many students bought lunch on Monday?
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