Page 464 - Basic College Mathematics with Early Integers

S E C T ION 6 .1 I PERCENTS, DECIMALS, AND FRACTIONS 441

Examples Write each percent as a decimal. PRACTICE 3–7
Write each percent as a decimal.
3. 23% = 2310.012=0.23 Replace the percent symbol with 0.01.Then multiply.
3. 89% 4. 2.7%
4. 4.6%=4.6(0.01)=0.046 Replace the percent symbol with 0.01.Then multiply. 5. 150% 6. 0.69%
7. 800%
5. 190%=190(0.01)=1.90 or 1.9
6. 0.74%=0.74(0.01)=0.0074

7. 100%=100(0.01)=1.00 or 1 We just learned
that 100% = 1

Work Practice 3–7

Concept Check Why is it incorrect to write the percent 0.033% as 3.3 in
decimal form?

Now let’s write percents as fractions.

Writing a Percent as a Fraction
1
Replace the percent symbol with its fraction equivalent, ; then multiply.
100
Don’t forget to simplify the fraction if possible.
1 43
43% = 43 # =
100 100

Examples Write each percent as a fraction or mixed number in simplest form. PRACTICE 8–12
Write each percent as a fraction
1 or mixed number in simplest
1 40 2 # 20 2
8. 40% = 40 # = = = form.
100 100 5 # 20 5
1 8. 25% 9. 2.3%
2
10. 225% 11. 66 %
1 1.9 3
9. 1.9% = 1.9 # = . We don’t want the numerator of the fraction to 12. 8%
100 100
10
contain a decimal, so we multiply by 1 in the form of 10 .
#
1.9 # 10 1.9 10 19
= = # =
100 10 100 10 1000
1
1 125 5 # 25 5 1
10. 125% = 125 # = = = or 1
100 100 4 # 25 4 4
1
1
#
1 1 100 1 100 1 1
11. 33a%=33 # = # = # =
3 100 3 100 3 100 3 Answers
1
Write as 3. 0.89 4. 0.027 5. 1.5 6. 0.0069
an improper fraction. 1 23
7. 8.00 or 8 8. 9.
4 1000
1 100 10. 9 or 2 1 11. 2 12. 2
12. 100% = 100 # = = 1 Just as we did in 4 4 3 25
100 100 Example 7, we confirm that
100% = 1 Concept Check Answer
Work Practice 8–12 To write a percent as a decimal, the
decimal point should be moved two
places to the left, not to the right. So
the correct answer is 0.00033.