8.5 problem solving using percent you can use percents to solve real life problems, such as...

8.5 Problem Solving Using Percent

You can use percents to solve real life problems, such as interpreting circle graphs or finding discounts.

Example In a survey conducted

by a local newspaper, adults were asked how many hours per week they spent exercising. Suppose 18 adults said they spent 7 or more hours per week.

Weekly Exercise Time

0 hours

45%

1-3 hr

33%

4-6 hours

17%

5%7 or more hours

Example - continued How many adults were

surveyed? Think…..What

information do we have?18 people said they

exercised for 7+ hours.That is 5% of the total. How would that be

written in the “is-of” statement?

18 is 5% of what number?

x adults360

18 5100x

5 1800x 5 5

Example - continued How many adults said 0

hours? Again…what do we know?

45% said they exercised for 0 hours.

There are a total of 360 adults How would that be written

in the “is-of” statement?

What number is 45% of 360?

x360

45100

100 16200x 100 100

x adults162

Discount Last weekend you

bought a jacket on sale for $63.75. Today you are shopping in the same store and notice that the jacket is being sold at the regular price of $75. What was the discount percent you received last weekend?

amount of discountoriginal price

%

100

75 63 7575 100

. x

11 2575 100.

x

75 75

75 1125x

x 15%

Increase or Decrease A percent of increase or percent of

decrease tells how much a quantity has changed.

The percent of change of a quantity is given by

actual changeoriginal amount

Examples 1995 profits - $235,000 1996 profits - $455,000 Find the percent of increase

members in 1996 – 422 members in 1997 – 394 Find the percent of

decrease455 000 235 000

235 000220 000235 000

, ,,

,,

x 94%

28442 100

x

x 7%

422 394422

28422

220 000235 000 100

,,

x