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Example This year Susan was given a 5% pay rise. If Susan earned £540 per week last year how much more will she get in her pay packet this year?. Finding the original percentage. Amount = 105% of 540 =. 1.05 x 540 =. £567. - PowerPoint PPT Presentation
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Finding the original percentageExample This year Susan was given a 5% pay rise. If Susan earned £540 per week last year how much more will she get in her pay packet this year?
Amount = 105% of 540 = 1.05 x 540 = £567
In reversing the process be aware of the mistake below that most usually make!Amount = 95% of 567 = 0.95 x 567 = £538.65
What we should have said isAmount = 105% of original = 1.05 x original = £567
original = £567 1.05
= £540
Finding the original percentageAlways use the following formula :
New value = Percentage of Original value
Or
New value = Percentage x Original value
ExampleAfter a pay rise of 5% Peter’s weekly pay is £126. How much did he earn before the rise?
New value = Percentage x Original value
Amount = 105% of original = 1.05 x original = £126
original = £126 1.05
= £120
ExampleAn electric toaster is offered in a sale at £32, after a reduction of 20%. What was the original price?
Amount = 80% of original = 0.80 x original = £32
original = £32 0.8
= £40
ExampleDuring a Grand Prix race, the tyres on a car are reduced in weight by 3%. If they weigh 388 kg at the end of the race, how much did they weigh at the start?
Amount = 97% of original = 0.97 x original = 388
original = 388 0.97
= 400 kg
ExampleThe population of Villanova has increased by 63% during the last five years and is now 124 000. What was its population five years ago?
Amount = 163% of original = 1.63 x original = 124 000
original = 124 000 1.63
= 76 073
ExampleThe price of houses in Villanova has increased by 18% during the last year. If the house costs $45 000 now, what would it have cost a year ago?
Amount = 118% of original = 1.18 x original = $45 000
original = 45 000 1.18
= $38 135.59
ExampleThe purchase price of a watch is £70.50. If this includes VAT at 17½%, find the price before VAT was added.
Amount = 117.5% of original = 1.175 x original = 70.50
original = 70.50 1.175
= £60
ExampleA car, which failed its MOT test, was sold for £585, thereby making a loss of 35% on the cost price. What was the cost price?
Amount = 65% of original = 0.65 x original = £585
original = 585 0.65
= £900
ExampleThe attendance of Burnley football club fell by 7% in 2001. If 2030 fewer people went to matches in 2001, how many went in 2000?
Amount = 7% of original = 0.07 x original = 2030
original = 2030 0.07
= 29 000
