1. Algebra 1
Section 3.4

2. Definition A percent is a ratio of a number to one hundred.
The symbol for percent is %.
Percents can be written with the symbol, as fractions, or as decimals.

3. Example 1
82% = 82
100 = 41 50
82% = 0.82

4. Example 2 = 3 5
0.6
0.6(100%) = 60%

5. Example 3
1.55(100%) = 155%
155% =
155
100 = 31 20

6. The percent of the whole is equal to the part:
The Percent Equation
The percent of the whole is equal to the part:
percent × whole = part

7. Example 4 What percent of 85 is 17? p × 85 = 17 p = 17 85 = 0.2

8. Example 5
What is 45% of 236?
r = 0.45(236)
r = 106.2

9. Example 6
78 is 130% of what number?
1.3w = 78
w = 78
1.3
= 60

10. Example 7 2% of the milk is butterfat. 0.02m = 1 m = 1 0.02 = 50
50 gal of 2% milk contains 1 gal of butterfat.

11. What percent of the votes did Miss Grandy receive?
Example 8
What percent of the votes did Miss Grandy receive?
What percent of 31,800 is 17,490?
p × 31,800 = 17,490

12. Yes, she won the election.
Example 8
p × 31,800 = 17,490
p =
17,490
31,800
= 0.55
p = 0.55(100%) = 55%
Yes, she won the election.

13. Homework: pp