Math Study Guide: Topic 4: Percents (pages 24-31)) Flashcards
What are other ways to say “percent?”
“hundredths”
“out of a hundred”
Example: 40% = 40 hundredths = 40 out of a hundred
How do you make a percent from a fraction?
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
How do you make a percent from a decimal?
Move the decimal two places to the right, and add a percent sign.
How do you change a percent to a decimal?
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)
How do you change a percent to a fraction?
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)
What is 50% written as a fraction and as a decimal?
½
.5
What is 25% written as a fraction and as a decimal?
¼
.25
What is 75% written as a fraction and as a decimal?
¾
.75
What is 33⅓% written as a fraction and as a decimal?
⅓
.3 INFINITY
What is 66⅔% written as a fraction and as a decimal?
⅔
.6 INFINITY
What is 12½% written as a fraction and as a decimal?
1/8
.125
What is 37½% written as a fraction and as a decimal?
3/8
.375
What is 62½% written as a fraction and as a decimal?
5/8
.625
What is 87½% written as a fraction and as a decimal?
7/8
.875
What is 16⅔% written as a fraction and as a decimal?
1/6
.16 INFINITY (.1666666)
What is 83⅓% written as a fraction and as a decimal?
5/6
.83 INFINITY (.833333)
What is 10% written as a fraction and as a decimal?
1/10
.10
What is 20% written as a fraction and as a decimal?
2/10 or 1/5
.20
What is 30% written as a fraction and as a decimal?
3/10
.30
What is 40% written as a fraction and as a decimal?
4/10 or 2/5
.40
What is 60% written as a fraction and as a decimal?
6/10 or 3/5
.60
What is 70% written as a fraction and as a decimal?
7/10
.70
What is 80% written as a fraction and as a decimal?
8/10 or 4/5
.80
What is 90% written as a fraction and as a decimal?
9/10
.90
If a question asks for a percent in a word problem, what do you actually need to do?
- Find the part and the whole
- Make a fraction, with the part on the top and the whole on the bottom
- 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)
If a question gives you the percent, but asks you for the part of the whole?
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)
