Warm Up

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Warm Up
Problem of the Day
Lesson Presentation
Lesson Quizzes
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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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4.8
1.5
13.5
25.84
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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 12. 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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Sunshine State Standards
MA.7.A.1.2 Solve percent problems, including
problems involving discountsand taxes
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The human body is made up mostly of water. In
fact, about 67 of a persons total (100) body
weight is water. If Cameron weighs 90 pounds,
about how much of his weight is water?
Recall that a percent is a part of 100. Since you
want to know the part of Camerons body that is
water, you can set up and solve a proportion to
find the answer.
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Additional Example 1A Using Proportions to Find
Percents of Numbers
Find the percent of each number.
30 of 50
30 100
n 50

Write a proportion.
30 50 100 n
Set the cross products equal.
1,500 100n
Multiply.
1,500
100n
Divide each side by 100 to isolate the variable.

100
100
15 n
30 of 50 is 15.
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Additional Example 1B Using Proportions to Find
Percents of Numbers
Find the percent of each number.
200 of 24
200 100
n 24

Write a proportion.
200 24 100 n
Set the cross products equal.
4,800 100n
Multiply.
4,800
100n
Divide each side by 100 to isolate the variable.

100
100
48 n
200 of 24 is 48.
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Check It Out Example 1A
Use proportional reasoning to find the percent of
each number.
40 of 18
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Check It Out Example 1B
Use proportional reasoning to find the percent of
each number.
120 of 400
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In addition to using proportions, you can find
the percent of a number by using decimal
equivalents.
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Additional Example 2A Using Decimal Equivalents
to Find Percents of Numbers
Find the percent of the number. Check whether
your answer is reasonable.
9 of 80
Write the percent as a decimal and multiply.
9 of 80 0.09 80
7.2
Model
Since 10 of 80 8, a reasonable answer for 9
of 80 is 7.2.
9
40
20
60
0
80
100
80
60
20
40
0
7.2
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Additional Example 2B Using Decimal Equivalents
to Find Percents of Numbers
Find the percent of the number. Estimate to check
whether your answer is reasonable.
0.6 of 270
Write the percent as a decimal and multiply.
0.6 of 270 0.006 270
1.62
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Check It Out Example 2
Use decimal equivalents to find the percent of
each number.
A.
6 of 18
B.
0.8 of 2000
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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?
Find 40 of 6,157 million.
0.40 6,157
Write the percent as a decimal.
2,462.8
Multiply.
The number of people 19 or younger was about
2,463 million.
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Check It Out Example 3A
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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Check It Out Example 3B
A bookstore finds that 55 of its total income in
March came from online orders. The total income
for March was 3,150. What was the income from
online orders?
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Check It Out Example 3C
There are 43,578 students in the public schools
of a city. About 38 of these students are
enrolled in middle school. About how many
students are enrolled in middle school?
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Lesson Quizzes
Standard Lesson Quiz
Lesson Quiz for Student Response Systems
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Lesson Quiz
Find the percent of each number. 1. 25 of 8
2. 40 of 110 Find the percent of each
number. Check whether your answer is
reasonable. 3. 150 of 96 4. 0.3 of 120 5.
Whitmer 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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44
144
0.36
357
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Lesson Quiz for Student Response Systems
1. Identify 75 of 4. A. 1 B. 2 C. 3 D. 4
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Lesson Quiz for Student Response Systems
2. Identify 30 of 120. A. 36 B. 38 C. 40 D. 42
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Lesson Quiz for Student Response Systems
3. Identify 140 of 85. A. 125 B. 120 C. 119 D.
109
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Lesson Quiz for Student Response Systems
4. Identify 0.6 of 130. A. 0.78 B. 0.80 C.
0.82 D. 0.86
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Lesson Quiz for Student Response Systems
5. A school has 250 students. If 56 of the
students went on a hiking trip, how many students
went on a hiking trip? A. 194 students B. 166
students C. 154 students D. 140 students