Basic Mathematics for College Students

580 Chapter 6 Percent

Remove the common factor of 4,000 from

the numerator and denominator. On the

left side, divide 600 by 4,000.

Write the decimal 0.15 as a percent.

The commission rate is 15%.

015%x

0.15

x4,000

1

4,000

1





To find percent of increase or decrease:

1.Subtract the smaller number from the larger

to find the amount of increase or decrease.

2.Find what percent the amount of increase or

decrease is of the original amount.

There are two methods that can be used to find

the unknown percent of increase (or decrease):

• The percent equation method


• The percent proportion method
  Caution!The percent of increase (or decrease)
  is a percent of the original number,that is, the
  number before the change occurred.  







WATCHING TELEVISION According to the Nielsen Company, the

average American watched 145 hours of TV a month in 2007. That

increased to 151 hours per month in 2008. Find the percent of increase.

Round to the nearest one percent.

First, subtract to find the amount of increase.

Subtract the smaller number from the larger number.

The number of hours watched per month increased by 6.

Next, find what percent of the original145 hours the 6 hour increase

represents.

The percent equation method:

is of

6  x  145 Translate.

Now, solve the percent equation.

To isolate xon the right side, divide both sides of

the equation by 145. Then remove the common

factor of 145 from the numerator and

denominator.

On the left side, divide 6 by 145.

Write the decimal 0.041 as a percent.

Round to the nearest one percent.

Between 2007 and 2008, the number of hours of television watched by

the average American each month increased by 4%.

If the percent proportion methodis used, solve the following proportion

for xto find the percent of increase.

is of

This is the proportion

to solve.

6

145



x

100

amount percent base

6 what percent 145?

4%x

004.1%x

0.041x

6

145



x 145

1

145

1

6 x 145

6 what percent 145?

151  145  6

The amount of discountis a percent of the

original price.

 

amount = percent  base

Notice that the formula is based on the percent

equation discussed in Section 6.2.

original

price

discount

rate

Amount of

discount  

TOOL SALES Find the amount of the discount on a tool kit if it is

normally priced at $89.95, but is currently on sale for 35% off. Then find

the sale price.

Write 35% as a decimal.

Do the multiplication.

Round to the neaerst cent

(hundredth).

$31.48

$31.4825

0.35$89.95

 35%  $89.95

Amount of discountdiscount rateoriginal price