Math Study Guide: Topic 4: Percents (pages 24-31))

Question 1

What are other ways to say “percent?”

Answer 1

“hundredths”

“out of a hundred”

Example: 40% = 40 hundredths = 40 out of a hundred

Question 2

How do you make a percent from a fraction?

Answer 2

Divide the numerator by the denominator, then multiply by 100 and add a percent sign.

or

Multiply the fraction by 100, reduce if possible, and add a percent sign

Question 3

How do you make a percent from a decimal?

Answer 3

Move the decimal two places to the right, and add a percent sign.

Question 4

How do you change a percent to a decimal?

Answer 4

Just cross off the percent sign and move the decimal point two places to the left.

Example: 75% = .75

(you are dividing by 100 and crossing off the percent sign)

Question 5

How do you change a percent to a fraction?

Answer 5

Just cross off the percent sign, put the number over 100, and reduce if possible.

Example: 75% = 75/100 = ¾

(you are dividing by 100 and crossing off the percent sign)

Question 6

What is 50% written as a fraction and as a decimal?

Answer 6

½

.5

Question 7

What is 25% written as a fraction and as a decimal?

Answer 7

¼

.25

Question 8

What is 75% written as a fraction and as a decimal?

Answer 8

¾

.75

Question 9

What is 33⅓% written as a fraction and as a decimal?

Answer 9

⅓

.3 INFINITY

Question 10

What is 66⅔% written as a fraction and as a decimal?

Answer 10

⅔

.6 INFINITY

Question 11

What is 12½% written as a fraction and as a decimal?

Answer 11

1/8

.125

Question 12

What is 37½% written as a fraction and as a decimal?

Answer 12

3/8

.375

Question 13

What is 62½% written as a fraction and as a decimal?

Answer 13

5/8

.625

Question 14

What is 87½% written as a fraction and as a decimal?

Answer 14

7/8

.875

Question 15

What is 16⅔% written as a fraction and as a decimal?

Answer 15

1/6

.16 INFINITY (.1666666)

Question 16

What is 83⅓% written as a fraction and as a decimal?

Answer 16

5/6

.83 INFINITY (.833333)

Question 17

What is 10% written as a fraction and as a decimal?

Answer 17

1/10

.10

Question 18

What is 20% written as a fraction and as a decimal?

Answer 18

2/10 or 1/5

.20

Question 19

What is 30% written as a fraction and as a decimal?

Answer 19

3/10

.30

Question 20

What is 40% written as a fraction and as a decimal?

Answer 20

4/10 or 2/5

.40

Question 21

What is 60% written as a fraction and as a decimal?

Answer 21

6/10 or 3/5

.60

Question 22

What is 70% written as a fraction and as a decimal?

Answer 22

7/10

.70

Question 23

What is 80% written as a fraction and as a decimal?

Answer 23

8/10 or 4/5

.80

Question 24

What is 90% written as a fraction and as a decimal?

Answer 24

9/10

.90

Question 25

If a question asks for a percent in a word problem, what do you actually need to do?

Answer 25

1. Find the part and the whole
2. Make a fraction, with the part on the top and the whole on the bottom
3. Convert that fraction to a percent

Example: A jar of 30 jelly beans has 9 pink jelly beans. What percent are pink?

9 is the part and 30 is the whole = 9/30 = 3/10 = 30% (of the jelly beans are pink)

Question 26

If a question gives you the percent, but asks you for the part of the whole?

Answer 26

Method 1:
Make a proportion equation: Part/Whole = Percent
(and then solve this equation)

Method 2:
Make the equation: Part = Percent x Whole
(and then solve this equation)