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Bell work:
Use Prime Factorization to reduce
20/39
Answer:
2x2x5
2x2x3x3
= 5/9
Lesson 11
Percents
S
In lesson 10 we compared fractions with
common denominators by rewriting them.
One way to express rational numbers with
common denominators is as percents. The
word percent means per hundred. The
denominator 100 is indicated by the word
percent or by the symbol %. One hundred
percent equals one whole.
We could say that 50% is also
50/100 which reduces to ½. 5%
means 5/100 which equals 1/20.
Write each percent as a reduced
fraction.
1%
10%
100%
Answer:
1% = 1/100
10% = 1/10
100% = 1
One way to write a fraction as a
percent is to find an equivalent
fraction with a denominator of
100.
¼ = 25/100 = 25%
Write each fraction as a percent.
¾
3/5
3/10
Answer:
¾ = 75/100 = 75%
3/5 = 60/100 = 60%
3/10 = 30/100 = 30%
Another way to convert a fraction
to a percent is to multiply the
fraction by 100%. This method
applies the Identity Property of
Multiplication since 100% is equal
to 1.
For example, to convert 2/3 to a percent
we can multiply 2/3 by 100% or 100%/1.
2/3 x 100%/1 = 200%/3
We complete the process by dividing 200%
by 3 and writing any remainder as a
fraction.
200%/3 = 66 2/3%
Write each fraction as a percent.
1/3
5/6
3/8
Answer:
1/3 = 100%/3 = 33 1/3%
5/6 = 500%/6 = 83 1/3%
3/8 = 300%/8 = 37 ½%
To write a percent as a fraction we replace
the percent sign with a denominator of
100 and reduce if possible. If the percent
is a mixed number, we rewrite it as an
improper fraction before multiplying the
denominator by 100 to remove the percent
symbol.
Write each percent as a reduced
fraction.
4%
40%
33 1/3%
Answer:
4% = 4/100 = 1/25
40% = 40/100 = 2/5
33 1/3% = 100%/3 = 100/300 = 1/3
Fractional part problems are often
expressed as percents. To perform
calculations with percents we first
convert the percent to a fraction or
decimal.
Example:
Forty percent of the 30 students
rode the bus. How many of the
students rode the bus?
Answer:
40% = 40/100 = 2/5
2/5 of 30 = 12
12 students rode the bus.
Example:
A quart is what percent of a
gallon?
Answer:
4 quarts equal a gallon so a quart
is ¼ of a gallon.
¼ = 25/100 = 25%
A quart is 25% of a gallon.
HW: Lesson 11 #1-30
Due Tomorrow