- Ratios and Percents
- The Relationship Between Fractions, Decimals, and Percents – Making Conversions
Inside Collection (Textbook): Derived copy of Fundamentals of Mathematics
Summary: This module is from Fundamentals of Mathematics by Denny Burzynski and Wade Ellis, Jr. This module discusses percents. By the end of the module students should understand the relationship between ratios and percents and be able to make conversions between fractions, decimals, and percents.
We defined a ratio as a comparison, by division, of two pure numbers or two like denominate numbers. A most convenient number to compare numbers to is 100. Ratios in which one number is compared to 100 are called percents. The word percent comes from the Latin word "per centum." The word "per" means "for each" or "for every," and the word "centum" means "hundred." Thus, we have the following definition.
Percent means “for each hundred," or "for every hundred."
The symbol % is used to represent the word percent.
The ratio 26 to 100 can be written as 26%. We read 26% as "twenty-six percent."
The ratio
We read 165% as "one hundred sixty-five percent."
The percent 38% can be written as the fraction
The percent 210% can be written as the fraction
Since one dollar is 100 cents, 25 cents is
Write the ratio 16 to 100 as a percent.
16%
Write the ratio 195 to 100 as a percent.
195%
Write the percent 83% as a ratio in fractional form.
Write the percent 362% as a ratio in fractional form.
Since a percent is a ratio, and a ratio can be written as a fraction, and a fraction can be written as a decimal, any of these forms can be converted to any other.
Before we proceed to the problems in Section 6 and Section 7, let's summarize the conversion techniques.
| To Convert a Fraction | To Convert a Decimal | To Convert a Percent |
| To a decimal: Divide the numerator by the denominator | To a fraction: Read the decimal and reduce the resulting fraction | To a decimal: Move the decimal point 2 places to the left and drop the % symbol |
| To a percent: Convert the fraction first to a decimal, then move the decimal point 2 places to the right and affix the % symbol. | To a percent: Move the decimal point 2 places to the right and affix the % symbol | To a fraction: Drop the % sign and write the number “over” 100. Reduce, if possible. |
Convert 12% to a decimal.
Note that 
The % symbol is dropped, and the decimal point moves 2 places to the left.
Convert 0.75 to a percent.
Note that ![]()
The % symbol is affixed, and the decimal point moves 2 units to the right.
Convert
We see in Example 7 that we can convert a decimal to a percent. We also know that we can convert a fraction to a decimal. Thus, we can see that if we first convert the fraction to a decimal, we can then convert the decimal to a percent.
Convert 42% to a fraction.
or
Convert 21% to a decimal.
0.21
Convert 461% to a decimal.
4.61
Convert 0.55 to a percent.
55%
Convert 5.64 to a percent.
564%
Convert
15%
Convert
137.5%
Convert
For the following 12 problems, convert each decimal to a percent.
0.25
25%
0.36
0.48
48%
0.343
0.771
77.1%
1.42
2.58
258%
4.976
16.1814
1,618.14%
533.01
2
200%
14
For the following 10 problems, convert each percent to a decimal.
15%
0.15
43%
16.2%
0.162
53.8%
5.05%
0.0505
6.11%
0.78%
0.0078
0.88%
0.09%
0.0009
0.001%
For the following 14 problems, convert each fraction to a percent.
20%
62.5%
28%
164%
945%
For the following 14 problems, convert each percent to a fraction.
80%
60%
25%
75%
65%
18%
12.5%
37.5%
512.5%
937.5%
((Reference)) Find the quotient.
((Reference))
((Reference)) Find the value of
((Reference)) Round 6.99997 to the nearest ten thousandths.
((Reference)) On a map, 3 inches represent 40 miles. How many inches represent 480 miles?
36 inches
"Used as supplemental materials for developmental math courses."