


Percents
A percent is another way to describe a part
of a whole (which means that percents are also another way to talk
about fractions or decimals). Percent literally means “of 100” in
Latin, so when you attend school 25 percent of the time, that means
you only go to school ^{25}
/_{100} (or .25)
of the time.
You would probably fail your classes if your attendance
percentage were that low, so don’t get any ideas from our example.
Instead, take a look at this question: 3 is what percent of 15?
This question presents you with a whole, 15, and then asks you to
determine how much of that whole 3 represents in percentage form.
Since a percent is “of 100,” to solve the question, you have to
set the fraction ^{3}/
_{15} equal to
^{x}/_{100} :
You then crossmultiply and solve for x:
Converting Percents into Fractions or Decimals
You should be skilled at converting percents into fractions
and decimals, because it will definitely come up on the Math IIC
test.
Percents directly relate to decimal numbers. A percent
is a decimal number with the decimal point moved two decimal places
to the left.
For example:
To convert from a decimal number to a percent, move the
decimal point two places to the right:
On an even simpler level, we can say, for example, that
50% = 0.5, or 22.346% = 0.22346. Percentages greater than 100 also
exist. 235% = 2.35, for example.
To convert from a percent to a fraction, take the percentage
number and place it as the numerator over the denominator 100. 58
percent is the same as ^{58}
/_{100} .
To convert from a fraction back to a percent, the easiest
method is to convert the fraction into a decimal first and then
change the resulting decimal into a percent.
For example:
