Percent Of Change

Percent of Change

• A special ratio is PERCENT.

• The word PERCENT means:

“out of”

1

0

0

35 35% = 100 99 99% = 100 12.5% = 12.5

100

So you can turn any percent into a ratio:

What if we DON’T KNOW a percent yet… how would we write the ratio??

??? % =

X

100

USE ALGEBRA !

EXAMPLE: 32 is what percent of 56?? Sorry, Mr. A You have to write it yourself!!

32 56

_x_ = 100

Set up your ratios…

…and solve it !!!

Percent CHANGE Sometimes we are asked to see how much something changes.

To find the Percent Change, follow these steps!

Original Price : $18 New Price : $10

DECREASE

$18 – $10 =

$8 $18

$8

What is the Percent Change in the price?

Increase or Decrease ??

By how much? Make a ratio comparing the change over the original

$8 = X 100 $1 8

Set the change ratio equal to the percent ratio

SOLVE IT !!!!

To find the percent of something, just set up a proportion! EXAMPLE: Sales Tax in Florida is 7%. How much tax will you pay for a $12,000 car?

X 7 = 100 12,000

• Remember a TAX is something you add to the original price.

• A DISCOUNT is something you subtract from the original price.