Form 2 Unit 8: Lesson 4 – Finding the Percentage Change

Objective

At the end of the lesson, students should be able to:

• Know how to find the percentage change.
• Find the percentages of a given quantity.

In this section we will look at how we can calculate percentage change. To find the percentage change (increase or decrease), we express the change in quantity as a percentage of the original quantity.

Therefore,

Percentage change (increase or decrease) = 

Where change = difference between original and new quantity.

Example 1

The price of a car increased from £1,560 in 2014 to £2,760 in 2015. Find the percentage increase in the cost of the car.

Solution

Change (increase in cost of car) = difference between original and new quantity

=£2,760 – £1,560 = £1,200

Example 2

A car costing £12,050 was reduced to £9,815. What was the percentage change?

Solution

Initial cost of car = £12,050.00

New cost of car = £9,815.00

Difference = £12,050 – £9,815.00  = £2,235.00

Example 3

A computer was sold at $1500 but it now sells at $1000. What is the percentage change in price?

Solution

Change (decrease in cost ) = difference between original and new quantity                                                                     =$1500 – $1000 =$500