1. Percents and Proportion
By, Mrs. Muller

2. Key Vocabulary Percent: A ratio that compares a number to 100
Proportion:
An equation stating that two ratios are equal.
Cross Products:
Cross multiplication, multiplying the numerator of each ratio with by the denominator of each ratio.

3. Finding Part of a Whole Procedure First write as a proportion.
Second write the cross products.
Third simplify
Fourth Isolate the variable. Use the Division Property of Equality.
Fifth and final step: Simplify

4. Example Finding part of a whole:
Find 45% of 32

5. Word Problem Example: Findinga whole amount
The 27 violinist make up 36% of the musicians in an orchestra. How many musicians are in the orchestra?

6. Example: Finding a Percent
What percent of 200 is 105?

7. Let’s Practice 80% of 72 = 57.6 3 is 60% of what number? =5
What percent of 25 is 16?
=64%
3% of 48
=1.44
6 is 80% of what number?
=7.5
What percent of 300 is 12?
=4%

8. Word Problem Practice
In an election with two candidates, the winner received about 72.2% of the 214,082 votes cast. By how many votes did the winner candidate win?
95,052 votes
The Library of Congress has almost 5 million maps. Maps make up just 3.85% of the library’s entire collection of items. How many items does the Library of Congress have?
About 130,000,000 items
Sarah got 13 problems right out of 20 problems on her test. What percentage of problems did she get correct?
65%