Download Percent Means Hundredths

Math 952
6.1 "Understanding Percent"
Objectives:
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Understand that percent means hundredths.
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Relate percent to fractions with denominator 100:
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Know how to compare pro…t with investment as a percent.
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Be able to change percents to decimals and decimals to percents.
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Be able to change fractions to percents and percents to fractions.
Percent Means Hundredths
The word percent comes from the Latin per centum, meaning "per hundred." So, percent means hundredths, or
percent is the ratio of a number to 100: The symbol % is called the percent symbol (or percent sign). This
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symbol can be treated as equivalent to the fraction
100 :
Example 1: (Fractions to percent)
Change the following fractions to percents.
125
90
b)
a)
100
100
c)
0:5
100
Percent Of Pro…t
Percent of pro…t is the ratio of money made to money invested. Generally, two investments do not involve the same
amount of money, and therefore, the comparative success of each investment cannot be based on the amount of pro…t. In
comparing investments, the investment with the greater percent of pro…t is considered the better investment.
Example 2: (Calculating the percent)
Calculate the percent of pro…t for both a and b, and tell which is the better investment.
a. A pro…t of $70 on a $700 investment.
b. A pro…t of $100 on a $1000 investment.
Example 3: (Calculating the percent)
Calculate the percent of pro…t for both a and b, and tell which is the better investment.
a. A pro…t of $300 on a $2000 investment.
b. A pro…t of $480 on a $4000 investment.
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Notes by Bibiana Lopez
Prealgebra by Franklin Wright
6.1
Decimals and Percents
One way to change a decimal number to a percent is to …rst change the decimal to fraction form with denominator 100
and then change the fraction to percent form.
To Change a Decimal to a Percent:
1: Move the decimal point two places to the right.
2: Add the % symbol.
Example 4: (Changing decimals to percents)
Change the following decimals to percents.
a) 0:3
b) 0:52
c) 0:004
d) 2
To Change a Percent to a Decimal:
1: Move the decimal point two places to the left.
2: Delete the % symbol.
Example 5: (Changing percents to decimals)
Change the following percents to decimals.
a) 8%
b) 150%
c) 12:5%
d) 15%
A Decimal Number that is:
1: less than 0:01 is less than 1%:
2: between 0:01 and 0:10 is between 1% and 10%:
3: between 0:10 and 1:00 is between 10% and 100%:
4: more than 1:00 is more than 100%:
Fractions and Percents
To Change a Fraction to a Percent:
1: Change the fraction to a decimal (Divide the numerator by the denominator).
2: Change the decimal to a percent.
Example 6: (Changing fractions and mixed numbers to percents)
Change the following fractions and mixed numbers to percents.
7
1
a)
b) 2
10
15
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Bibiana Lopez
Prealgebra by Franklin Wright
c)
6.1
5
8
d) 3
3
5
To Change a Percent to a Fraction or Mixed Number:
1: Write the percent as a fraction with denominator 100 and delete the % symbol.
2: Reduce the fraction.
Example 7:
Change the following percents to fractions or mixed numbers in reduced form.
a) 15 41 %
b) 16 32 %
c) 50%
d) 0:75%
Example 8: (Word Problem)
A department store o¤ers a 35% discount during a special sale on dresses. Change 35% to a fraction reduced to lowest
terms.
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Bibiana Lopez