1. Percents and Proportions
COURSE 3 LESSON 6-3
Percents and Proportions
12 is 40% of what number?
A diagram can help you understand the problem. 12 w = 40
100
Write a proportion.
12 • 100 = 40w
Write the cross products.
1,200 = 40w
Simplify. =
1,200 40
40w
Divide each side by 40.
30 = w
Simplify.
6-3

2. Percents and Proportions
COURSE 3 LESSON 6-3
Suppose 11,550 elementary students make up 14% of a city’s population. What is the population of the city?
A diagram can help you understand the problem.
11,500 w 14
100 =
Write a proportion.
11,550 • 100 = 14w
Write the cross products.
1,155,000 = 14w
Simplify. =
Divide each side by 14.
1,155,000 14
14w
82,500 = w
Use a calculator.
6-3

3. Percents and Proportions
COURSE 3 LESSON 6-3
Percents and Proportions
(continued)
The population of the city is 82,500 people.
Check for Reasonableness 82,500 is about 80,000. Since 14% of 80,000 is 11,200, which is close to 11,155, the answer is reasonable.
6-3

4. Percents and Proportions
COURSE 3 LESSON 6-3
26 is what percent of 80?
A diagram can help you understand the problem. 26 80 p
100 =
Write a proportion.
26 • 100 = 80p
Write the cross products.
2,600 = 80p
Simplify.
2,600 80
80p =
Divide each side by 80.
32.5% = p
Simplify and insert a percent sign.
6-3

5. Percents and Proportions
COURSE 3 LESSON 6-3
1. Find 25% of 160.
2. 15 is what percent of 12?
3. 32 is 20% of what number? 40
125%
160
6-3