Percentage Change

OCR Module 8

Change?

• An Increase

• A Decrease

For example

• Increase £24 000 by 3%

3% of 24000

= 24000 x 3 100

= £720

Total = £24 720 103% of 24000

= 24000 x 103 100

= £24 720

MULTIPLIER of 1.03

For example

• Decrease £17.60 by 15%

85% of 17.60

= £14.96

Left with 85% of 17.60

= 17.60 x 0.85

MULTIPLIER of 0.85

What is the Multiplier for …

An INCREASE of

12%

25%

33%

17.5%

1.12

1.25

1.33

1.175

A DECREASE of

12%

25%

33%

17.5%

0.88

0.75

0.67

0.825

The Original Value?

• Often, we are given a price AFTER an increase or decrease

• To calculate this, we complete a REVERSE PERCENTAGE calculation

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%

MULTIPLIER= 1.10

110% of OLD = 38 500

OLD x 1.10 = 38 500

OLD = 38500 ÷ 1.10

OLD SALARY = £35 000

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%

MULTIPLIER= 0.80

80% of OLD = 26.00

OLD x 0.80 = 26.00

OLD = 26.00 ÷ 0.80

OLD PRICE = £32.50