Notes on Calculating Percent

By Proportion

There are
three basic percent problems:

1)
What **is** 15**%** **of** 180?

2)
12 **is** what **percent** **of** 95?

3)
60 **is ** 40**%** **of** what number?

We break these problems into
**three** parts: Is, Of,
and percent and we use a Magic Formula!

_{}

Just plug in the numbers and solve by proportion!

1)
What **is**
15**%** **of** 180?

We
don’t know the “**is”**, so we use a variable, *n*. The “of” is 180. So using the formula

_{} we place_{}, since the percent is 15%.
Then we solve it like a proportion,

100*n* =
15∙180

__100 n__ =

100
100

*n* = 27 so we can answer: **27** is 15% of 180.

2)
12 **is** what **percent** **of** 95?

In this problem, 12 is the “is”, 95 is the
“of” and *n* is the percent. So
plug it in!

_{} we place_{} and solve by proportion:

__95 n__
=

95
95

*n*
= 12.63 round to about 13 % so we answer

12
is about 13% of 95

3)
60 **is ** 40**%** **of** what number?

In this problem, 60 is the “is”, *n*
is the “of” and 40 is the percent. So plug it in!

_{} we place_{} and solve by proportion:

__6000__ = __40 n__

40 40

150
= *n*

So we answer 60 is 40% of 150.

Unfortunately not all
percent problems are worded so easily: Link
here to see other wording: