Percentages There are 3 Types of

Percentages

There are 3 Types of % questions • 1 st Type FIND “some” % OF “something else” • Remember “OF” means “multiply by” – Per cent means “per 1 hundred” so 35% of 200 means “ 35 out of a hundred” x 200, i. e. • Three steps to work it out are: i. Write out question as e. g. 43% of 300; ii. Then as iii. Remember to check your Answer

…continued - 3 Types of % questions • 2 nd Type Express “one thing” AS A PERCENTAGE OF “another” • Four steps to work it out are: i. Write fraction with smallest number on top; ii. Then write decimal, and iii. Multiply by 100 iv. Check your answer 12 80 X 100

…continued - 3 Types of % questions • 2 nd Type continued – Percentage Change • This is still about determining the change in value as a percentage of “another value” and is therefore still Type 2 • Not much to worry about here – just an equation which is illustrated below with an example Percentage “Change” With an example using profit Percentage “Profit”

…continued - 3 Types of % questions • 3 rd Type • These are identified by them not giving you the Original Value • If its increasing in value, e. g. “A house increases in value by 25% to £ 90000. Find its value before the rise”, then the steps are: i. Set the increased amount equal to (100 + the % increase); ii. Then divide through by new high value to find 1% iii. Multiply by 100 to get 100% iv. Check your answer – Does 72000 seem reasonable?

…continued - 3 Types of % questions • 3 rd Type continued • If its decreasing in value, e. g. “A house decreases in value by 21% to £ 102000. Find its value before the rise”, then the steps are: i. Set the decreased amount equal to (100 - the % increase); ii. Then divide through by new low value to find 1% iii. Multiply by 100 to get 100% iv. Check your answer – Does 129113 seem reasonable? v. Don’t forget you can back calculate using (102000 129113) x 100 which gives 79% or use the percentage change formula in Type 2 to see that it is a 21% fall in price.

…Sales type questions • A shop has a sale – it starts Tues and finishes Saturday. Each day items fall by 15% of their previous day’s value. i. A coat starts on Mon at £ 19. 95, what is it on Wednesday? ii. £ 19. 95 x 0. 85 = y iii. y x 0. 85 = £ 14. 41