Relating Decimals, Fractions, and Percents

1
Relating Decimals, Fractions, and
Percents

• 8.1

Pre-Algebra
2
Warm Up
Evaluate. 1. 2. 3. 4.


14
?
3
Learn to relate decimals, fractions, and
percents.
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Vocabulary
percent
5
Percents are ratios that compare a number to 100.
30
50
75
6
(No Transcript)
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To convert a fraction to a decimal, divide the
numerator by the denominator.
To convert a decimal to a percent, multiply by
100 and insert the percent symbol.
0.125 ? 100 ? 12.5
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Example Finding Equivalent Ratios and Percents
Find the missing ratio or percent equivalent for
each letter ag on the number line.
a
10
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Example Finding Equivalent Ratios and Percents
Find the missing ratio or percent equivalent for
each letter ag on the number line.
b
0.25
25
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Example Finding Equivalent Ratios and Percents
Find the missing ratio or percent equivalent for
each letter ag on the number line.
c
40
11
Example Finding Equivalent Ratios and Percents
Find the missing ratio or percent equivalent for
each letter ag on the number line.
d
0.60
60
12
Example Finding Equivalent Ratios and Percents
Find the missing ratio or percent equivalent for
each letter ag on the number line.
e
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Example Finding Equivalent Ratios and Percents
Find the missing ratio or percent equivalent for
each letter ag on the number line.
0.875
f
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Example Finding Equivalent Ratios and Percents
Find the missing ratio or percent equivalent for
each letter ag on the number line.
g
125
15
Try This
Find the missing ratio or percent equivalent for
each letter ag on the number line.
e
c
50
12
g
25
75
1
a
b
d
f
0.125
a
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Try This Continued
Find the missing ratio or percent equivalent for
each letter ag on the number line.
e
c
50
12
g
25
75
1
a
b
d
f
b
25
17
Try This Continued
Find the missing ratio or percent equivalent for
each letter ag on the number line.
e
c
50
12
g
25
75
1
a
b
d
f
c
0.375
37
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Try This Continued
Find the missing ratio or percent equivalent for
each letter ag on the number line.
e
c
50
12
g
25
75
1
a
b
d
f
d
50
19
Try This Continued
Find the missing ratio or percent equivalent for
each letter ag on the number line.
e
c
50
12
g
25
75
1
a
b
d
f
e
0.625
62
20
Try This Continued
Find the missing ratio or percent equivalent for
each letter ag on the number line.
e
c
50
12
g
25
75
1
a
b
d
f
f
75
21
Try This Continued
Find the missing ratio or percent equivalent for
each letter ag on the number line.
e
c
50
12
g
25
75
1
a
b
d
f
100

g
1
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Example Finding Equivalent Fractions, Decimals,
and Percents
Find the equivalent fraction, decimal, or percent
for each value given on the circle graph.
0.15(100) 15
0.12(100) 12
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Example Continued
You can use information in each column to make
three equivalent circle graphs. One shows the
breakdown by fractions, one shows the breakdown
by decimals, and one shows the breakdown by
percents.
The sum of the fractions should be 1.
The sum of the decimals should be 1.
The sum of the percents should be 100.
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Try This
Fill in the missing pieces on the chart below.
0.1(100) 10
0.45
0.25
0.25(100) 25
0.2
0.2(100) 20
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Example Physical Science Application
Gold that is 24 karat is 100 pure gold. Gold
that is 14 karat is 14 parts pure gold and 10
parts another metal, such as copper, zinc,
silver, or nickel. What percent of 14 karat gold
is pure gold?
Set up a ratio and reduce.
7 ? 12
Find the percent.
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Try This
A bakers dozen is 13. When a shopper purchases
a dozen items at the bakery they get 12. It is
said that the baker eats 1 item from every batch.
So, what percentage of the food the baker cooks
is eaten without being sold?
Set up a ratio and reduce.
1 ? 13
0.077
Find the percent.
7.7
So the baker, eats 7.7 of the items they bake.
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Lesson Quiz
Find each equivalent value. 1. as a percent 2.
20 as a fraction 3. as a decimal 4. as
a percent 5. About 342,000 km2 of Greenlands
total area (2,175,000 km2) is not covered with
ice. To the nearest percent, what percent of
Greenlands total area is not covered with ice?
37.5
0.625
56
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