Page 486 - Basic College Mathematics with Early Integers

S E C T I O N 6.3 I SOLVING PERCENT PROBLEMS USING PROPORTIONS 463

Example 10 Solving Percent Proportion for the Percent PRACTICE 10

What percent of 40 is 6?
What percent of 50 is 8?

t
T T T
Solution: percent base amount

8 p 4 p 8
= or = Write the proportion and simplify .
50 100 25 100 50
#
#
4 100 = 25 p Set cross products equal.
#
400 = 25 p Multiply.
400
= p Divide 400 by 25, the number multiplied by p.
25
16 = p Simplify.
So, 16% of 50 is 8.
Work Practice 10
Recall from our percent
proportion that this number already
is a percent. Just keep the number as
is and attach a % symbol.

Example 11 Solving Percent Proportion for the Percent PRACTICE 11
336 is what percent of 160?
504 is what percent of 360?

t
T T T
Solution: amount percent base
504 p
=
360 100
504
Let’s choose not to simplify the ratio .
360
#
#
504 100 = 360 p Set cross products equal.
#
50,400 = 360 p Multiply.
50,400
= p Divide 50,400 by 360, the number multiplied by p.
360
140 = p Simplify.
504
Notice that by choosing not to simplify , we had larger numbers in our equation.
360
Either way, we find that 504 is 140% of 360.
Work Practice 11

You may have noticed the following while working examples.

Use the following to see whether your answers are reasonable.
100% of a number = the number

a percent
a number larger
£greater than≥ of a number = than the original number
100%
a percent a number less
a b of a number =
less than 100% than the original number Answers
10. 15% 11. 210%