6-6
Pre-Algebra .
Proportions and Percents
Objectives: 1.
2.
OBJECTIVE
1
EXAMPLE 1
Finding Part of a Whole
Finding Part of a Whole
Find 65% of 245.
STEPS
1. Write a proportion.
2. Write cross products.
3. Divide each side by 100.
4. Simplify.
Solve each proportion.
1. 25% of 124 is
.
2. 43% of 230 is
.
3. 12.5% of 80 is
.
EXAMPLE 2
Finding a Percent
What percent of 60 is 52? Round to the nearest tenth of a percent.
STEPS
1. Write a proportion.
2. Write cross products.
3. Divide each side by 60.
4. Simplify.
5. Round
Solve each proportion.
1. What percent of 250 is 138?
2. 14 is what percent of 15?
3. What percent of 34 is 28?
OBJECTIVE
2
Finding a Whole Amount
Sometimes you know the percent that a part represents, and you want to find the whole
amount. For example, your class fundraising committee might announce, “We’ve
collected $207 so far, which is 46% of our goal!” You can use a proportion to calculate the
goal.
EXAMPLE 3
Finding the Whole Amount
207 is 46% of what number?
STEPS
1. Write a proportion.
2. Write cross products.
3. Divide each side by 46.
4. Simplify.
Solve each proportion.
1. 19 is 75% of what number?
EXAMPLE 4
2. 310 is 99% of what number?
Real-World Problem Solving
In 2000, the number of drive-in
movie screens in the U.S. was
about 78% of the number in
1990. About how many drive-in
screens were there in 1990?
3. 216 is 72% of what number?
Pre-Algebra Objectives 6.6
The student should be able….
1. To find a part of a whole and a percent.
2. To find a whole amount.