Decimals (1)

1. Percents
3.2
3.2
1. Write a percent as a fraction or decimal number.
2. Write a fraction or decimal number as a percent.
3. Translate and solve percent sentences.
4. Solve problems involving percents.

2. Review
Review
d
c
b
a

Ratio: A comparison of two quantities using a quotient (fraction).
Proportion: Two ratios set equal.
Cross
Products:
Cross products are equal.
Percent:
20% = 20 out of 100
0
20
10

1
or 0.2
5

A ratio representing some part out of 100.
bc
ad 

3. Percents to Decimals
Percents to Decimals
55%
Drop % and move decimal point 2 places to the left.
=.55
38% =.38
14.5% =.145
.25% =.0025
%
2
1
45 %
.5
45
 455
.


4. Percents to Fractions
Percents to Fractions
55%
Change to a decimal, then Read It, Write It, Reduce It
=.55
38% =.38
14.5% =.145
.25% =.0025
%
2
1
45 %
.5
45
 455
.

100
55

20
11

100
38

50
19

1000
145

200
29

10000
25

400
1

1000
455

200
91


5. Decimals to Percents
Decimals to Percents
Move the decimal point 2 places to the right and add %.
= 55%
.55
= 38%
.38
= 250%
2.5
= .3%
.003

6. Fractions to Percents
Fractions to Percents
Change to a decimal and then to a percent.
4
3
75
.
 %
75

8
5
625
.
 %
.5
62

5
2
3 4
3.
 %
340


7. Slide 1- 7
Copyright © 2011 Pearson Education, Inc.
What is 7/8 as a percent?
a) 78%
b) 87%
c) 87.5%
d) 718%
3.2

8. Slide 1- 8
Copyright © 2011 Pearson Education, Inc.
What is 7/8 as a percent?
a) 78%
b) 87%
c) 87.5%
d) 718%
3.2

9. Percent Sentences
Percent Sentences
A percent of a whole is a part of the whole.
% multiply total
(follows “of”)
part
=
36% of 72 is what number?
.36 ∙ 72 = x
.36 (72) = x
25.92 = x
36% of 72 is 25.92.

10. Percent Sentences
Percent Sentences
A percent of a whole is a part of the whole.
% multiply total part
=
.42 ∙ x = 31.92
.42 x = 31.92
x = 76
42% of what number is 31.92?
42% of 76 is 31.92.

11. Percent Sentences
Percent Sentences
x ∙ 63 = 56
63 x = 56
x = .8888888…
88.9% of 63 is 56.
What percent of 63 is 56?
x = 88.9%

12. Slide 1- 12
Copyright © 2011 Pearson Education, Inc.
2.4% of 130 is what number?
a) 31.2
b) 3.12
c) 1.83
d) 0.18
3.2

13. Slide 1- 13
Copyright © 2011 Pearson Education, Inc.
2.4% of 130 is what number?
a) 31.2
b) 3.12
c) 1.83
d) 0.18
3.2

14. Slide 1- 14
Copyright © 2011 Pearson Education, Inc.
What percent of 48 is 51.84?
a) 93%
b) 98%
c) 108%
d) 109%
3.2

15. Slide 1- 15
Copyright © 2011 Pearson Education, Inc.
What percent of 48 is 51.84?
a) 93%
b) 98%
c) 108%
d) 109%
3.2

16. Percent Sentences
Percent Sentences
.06 x = 100
x = 1666.66666
Sentinel has 1,667 employees.
Percent ∙ whole = part
x = 1667
On Monday, January 17, 2012, the Morning Sentinel
reported it planned to cut 100 full-time jobs in a bid
to return to profitability. This is 6% of the
newspaper’s workforce. How many employees does
the Sentinel have?
Percent: 6% = .06
Whole: x
Part: 100

17. Percent Sentences
Percent Sentences
.07(570) = x
x = 39.90
Total cost is $609.90.
Percent ∙ whole = part
What did we find?
Jamal purchases a new surfboard that costs $570.
The sales tax is 7%, what is the total cost of the
surfboard?
Percent: 7% = .07
Whole: 570
Part: x
Sales tax.
Total cost = cost plus tax.
90
39
00
570
.
.
90
609.