Percentage Change

1
Percentage Change

• OCR Module 8

2
Change?

• An Increase
• A Decrease

3
For example

• Increase 24 000 by 3

3 of 24000
720
24 720
Total 24 720
103 of 24000
4
For example

• Decrease 17.60 by 15

Left with 85 of 17.60
85 of 17.60
MULTIPLIER of 0.85
17.60 x 0.85
14.96
5
What is the Multiplier for
An INCREASE of 12 25 33 17.5
A DECREASE of 12 25 33 17.5
1.12
0.88
1.25
0.75
1.33
0.67
1.175
0.825
6
The Original Value?

• Often, we are given a price AFTER an increase or
  decrease
• To calculate this, we complete a REVERSE
  PERCENTAGE calculation

7
For example
After a 10 salary increase, David earned 38500
What was his salary BEFORE this increase?
NEW SALARY is the OLD SALARY plus 10
110 of OLD 38 500
MULTIPLIER 1.10
OLD x 1.10 38 500
OLD 38500 1.10
OLD SALARY 35 000
8
For example
A shirt was ON SALE for 26.00. It had been
reduced by 20. What was the original price?
SALE PRICE is the OLD PRICE less 20
80 of OLD 26.00
MULTIPLIER 0.80
OLD x 0.80 26.00
OLD 26.00 0.80
OLD PRICE 32.50