1. Percents
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
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
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3. 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
.
9. 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
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
x ∙ 63 = 56
63 x = 56
x = .8888888…
88.9% of 63 is 56.
What percent of 63 is 56?
x = 88.9%
16. 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
.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.