Solve each proportion.

1. 2.

3. 4.

c6

1215

= 2112

7y

=

3 + x7

48

= 2 + xx – 4

2535

=

4.8 4

12

–17

Math on the Mind

PercentsUnit 4, Lesson 11Mrs. King

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Let’s refresh our memory:

•http://www.brainpop.com/math/ratioproportionandpercent/percents/preview.weml

What does percent mean?

•“per” means out of•“cent” means 100

▫How many years in a “century”?▫How many “cents” in a dollar?▫How many legs on a “centipede”?

Converting Percents to Decimals•To change a percent to a decimal, drop

the % sign and move the decimal point 2 places to the left

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Convert each percent to a decimal:

▫17%

▫5%

▫23%

▫236%

▫8%

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0.1

70.05

0.23

2.36

0.08

Converting Decimals to Percents

•To change a decimal to a percent, move the decimal point 2 places to the right and attach a % sign.

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Convert the decimal to a percent:

▫.08 =

▫3.26 =

▫.75 =

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8%

326%

75

%

Change to a

Decimal

Calculating Percents: The Equation Method

How much is 11% of $400?

The unknow

n!

The unknow

n!

“Equals”

“Equals”Change

to a decimal

“Multiply”

“Multiply”

$400

$400

x 11.0 40044x

Example #1

•15% of 650 is what number?

15. 650 xx5.97

Example #2

•What is 12% of 250?

x 12. 25030x

Proportions to remember!

whole

partpercent

100 of

ispercent

100

Calculating Percents: The Proportion Method

How much is 11% of $400?

of

ispercent

100

400100

11 x

x1004400

x44

Example #3

•15% of 650 is what number?

of

ispercent

100

650100

15 x

x1009750

x50.97

Example #4

•What is 12% of 250?

of

ispercent

100

250100

12 x

x1003000

x30

Percentage Problems•15 is what percent of 50?

•16 is 22% of what number?

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Percentage Problems•91 is what percent of 364?

•What is 9.5% of 75,000?

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Try these on your own:• 42 is what percent of

112?

• What percent of 38 is 19?

• What is 0.5% of 2350?

• http://www.quia.com/mc/499417.html

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