6.2 Students will use proportions to solve percentage problems.
Warm Up
Rewrite each value as indicated.
1. 24 as a percent
50
48%
1
2. 25% as a fraction
4
3. 3 as a decimal
8
0.375
4. 0.16 as a fraction 4
25
6.2 Students will use proportions to solve percentage problems.
Explain It!
6.2 Students will use proportions to solve percentage problems.
General Objective
Students will use proportions to solve
percentage problems.
6.2 Students will use proportions to solve percentage problems.
Where do we use percents?
6.2 Students will use proportions to solve percentage problems.
The Percent Proportion
number
part
=
100
Whole (of)
12 is what % of 40?
6.2 Students will use proportions to solve percentage problems.
Example 1: Finding the Percent One Number Is of Another
What percent of 92 is 66?
Method 1: Set up a proportion to find the percent.
Think: What number is to 100 as 66 is to 92?
number
part
=
100
whole
n
= 66
92
100
Set up a proportion.
n
Find the cross products.

92 = 100

92n = 6600
66
Substitute.
Simplify.
6.2 Students will use proportions to solve percentage problems.
Additional Example 1 Continued
92n = 6600
92
92
n ≈ 72
Divide both sides by 92.
Simplify.
66 is approximately 72% of 92.
6.2 Students will use proportions to solve percentage problems.
Try It! Example 1
What percent of 140 is 21?
Method 1: Set up a proportion.
Think: What number is to 100 as 21 is to 140?
number
part
=
100
whole
n
= 21
140
100
n

140 = 100
Set up a proportion.
Let n represent the percent.

140n = 2100
21
Find the cross products.
Simplify.
6.2 Students will use proportions to solve percentage problems.
Try It! Example 1 Continued
140n = 2100
140
140
n = 15
21 is 15% of 140.
Divide both sides by 140.
Simplify.
6.2 Students will use proportions to solve percentage problems.
Practice:
Green: 1, 3
Red: 2, 5
Blue: 3, 4
1. What percent of 80 is 20? 25%
2. What percent of 48 is 16? 33 1/3%
3. 300 out of 1000 is what percent? 30%
4. 70 is what percent of 35? 200%
5. A bin contains 120 ears of white and yellow corn. Of these,
78 ears are yellow. What percent of the ears of corn are
yellow? What percent are white?
65%; 35%
6.2 Students will use proportions to solve percentage problems.
Lesson Quiz: Part
Find each percent.
1. What percent of 75 is 15?
20%
6.2 Students will use proportions to solve percentage problems.
Lesson Quiz for Student Response Systems
1. What percent of 75 is 15?
A. 5
B. 10
C. 20
D. 50
6.2 Students will use proportions to solve percentage problems.
Lesson Quiz for Student Response Systems
3. 120 is what percent of 50?
A. 12
B. 50
C. 240
D. 600