5.5

1
5.5

• Solving Commission, Percent of Increase or
  Decrease, and Interest Problems

2
Solving Commission Problems
The amount of money a person makes that is a
percentage of the value of sales is called a
commission. It is calculated by multiplying the
percentage (called the commission rate) by the
value of the sales.
Commission commission rate ? value of sales
Example A salesperson has a commission rate of
18.5. He sells 43,250 worth of goods. What is
his commission?
Commission commission rate ? value of sales
18.5 ? 43,250
0.18.5 ? 43,250
8001.25
His commission is 8,001.25.
3
Solving Increase Decrease Problems
We sometimes need to find the percent by which a
number increases or decreases.
Example The cost of a certain car increased from
16,000 last year to 17,280 this year. What was
the percent of increase?
Amount of increase original amount new amount
17,280 16,000 1280
The cars cost increased by 8.
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Solving Increase Decrease Problems
Example Patrick weighed 285 pounds two years
ago. After dieting, he reduced his weight to 171
pounds. What was the percent of decrease in his
weight?
Amount of decrease original amount new amount
285 171 114
Patricks weight decreased by 40.
5
Solving Simple Interest Problems
Interest is money paid for the use of money. The
principal is the amount deposited or borrowed.
The interest rate is per year, unless otherwise
stated. If the interest rate is in years, the
time must also be in years.
Interest principal ? rate ? time I P ? R ? T
Example Find the simple interest on a loan of
3600 borrowed at 6 for 8 years.
I P ? R ? T
3600 ? 0.06 ? 8
The interest earned is 1,728.
1728