# FINDING PERCENT INCREASE AND DECREASE

Finding Percent Increase and Decrease :

In our day to day life, often we may see the situations where the values will change.

For example,

Increase in wages

Increase / Decrease in price of an item

Increase / Decrease in temperature

In this section, we will learn the increase or decrease of a value in terms of percent.

That is, we will calculate, how much a value is increased or decreased per hundred.

For example, a laptop is originally priced \$2500, but Richard gets it for \$2250.

The actual decrease he gets in the price of the laptop is \$250.

Here, the percent decrease is, how much the price is decreased per hundred.

In 2500, there are 25 hundreds.

For 25 hundreds (2500), he gets a decrease of 250.

Find the decrease for 1 hundred.

That is,

=  250 / 25

=  10

So, for each \$100 of the price, he gets a decrease of \$10.

This is called percent decrease.

Therefore, the price of the laptop is decreased by 10 percent.

## Finding Percent Increase and Decrease - Formula

The formula given below can be used to find the percent increase or decrease of a value.

The change may be an increase or a decrease.

Here, the original amount is the value before increase or decrease.

## Finding Percent Increase and Decrease - Examples

Example 1 :

What is the percent increase from \$5 to \$8 ?

Solution :

Step 1 :

Find the amount of change.

Amount of change  =  Greater value - Lesser value

=  8 - 5

=  3

Step 2 :

Percentage change is

=  (Amount of change / Original amount) x 100 %

=  (3 / 5) x 100%

=  0.6 x 100 %

=  60 %

Hence, the percent increase from \$5 to \$8 is 60%.

Example 2 :

Amber got a raise, and her hourly wage increased from \$8 to \$9.50. What is the percent increase?

Solution :

Step 1 :

Find the amount of change.

Amount of change  =  Greater value - Lesser value

=  9.50 - 8.00

=  1.50

Step 2 :

Find the percent increase. Round to the nearest percent.

Percentage change is

=  (Amount of change / Original amount) x 100 %

=  (1.50 / 8.00) x 100%

=  0.1875 x 100 %

=  18.75 %

≃  19 %

Hence, Amber's hourly wage is increased by 19%.

Example 3 :

The price of a pair of shoes increases from \$52 to \$64. What is the percent increase to the nearest percent?

Solution :

Step 1 :

Find the amount of change.

Amount of change  =  Greater value - Lesser value

=  64 - 52

=  12

Step 2 :

Find the percent increase. Round to the nearest percent.

Percentage change is

=  (Amount of change / Original amount) x 100 %

=  (12 / 52) x 100%

=  0.2307 x 100 %

=  23.07 %

≃  23 %

Hence, the price of a pair of shoes increased by 23%.

Example 4 :

In a class, students strength has been increased from 20 to 30. What percent of strength is increased ?

Solution :

Step 1 :

Find the amount of change.

Amount of change  =  Greater value - Lesser value

=  30 - 20

=  10

Step 2 :

Find the percent increase. Round to the nearest percent.

Percentage change is

=  (Amount of change / Original amount) x 100 %

=  (10 / 20) x 100%

=  0.5 x 100 %

=  50 %

Hence, the strength is increased by 50%.

Example 5 :

Mr. David monthly salary is revised from \$2500 to \$2600. What percentage is the salary increased ?

Solution :

Step 1 :

Find the amount of change.

Amount of change  =  Greater value - Lesser value

=  2600 - 2500

=  100

Step 2 :

Find the percent increase. Round to the nearest percent.

Percentage change is

=  (Amount of change / Original amount) x 100 %

=  (100 / 2500) x 100%

=  0.04 x 100 %

=  4 %

Hence, David's monthly salary is increased by 4%.

After having gone through the stuff given above, we hope that the students would have understood, how to solve problems on percent increase or decrease.

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