Percentages - Decimal Multipliers

Use DECIMAL MULTIPLIER and SHOW WORKING


Method
Percentage increase using Decimal Multipliers
For the explanation I will assume it's a 20% increase of a quantity 50
step 1 -  add increase to 100%: 100% + 20% = 120%
step 2 - divide this by 100: 120%÷ 100 = 1.2
step 3 - times quantity 50 by 1.2: 50 x 1.2 = 60


So 50 increased by 20% is 60


Percentage decrease using Decimal Multipliers
For the explanation I will assume it's a 20% decrease of a quantity 50
step 1 -  subtract decrease from 100%: 100% - 20% = 80%
step 2 - divide this by 100: 80% ÷ 100 = 0.8
step 3 - times quantity 50 by 0.8: 50 x 0.8 = 40 


So 50 decreased by 20% is 40


Also see BBC website below for more explanation and examples


http://www.bbc.co.uk/skillswise/numbers/fractiondecimalpercentage/percentages/percentincrease/factsheet5.shtml



Questions


1.My salary was £230 per week before I got a 7% pay rise. What is my new salary?
£230 x 1.07 =


2.The price of a TV is reduced by 15%. If it cost £500 before the reduction, what was it after?
£500 x 0.85 =


3.The price of an England shirt dropped by 20% after the World Cup, it was £35 before. How much was it after?


4.A house’s price increased 20% in 4 years, it was £230 000 4 years ago, how much is it now?


5.The number of boys in a school increased by 5% from 670 last year.
How many boys are there in the school this year?


6.VAT is 17.5%, add VAT to the following items giving your answers to 2 d.p..


Prices before VAT
a.  TV - £400
b.  Ipod - £70
c.  Laptop - £356


7. After an increase of 37% a house cost Richard £137 000. He wants to know how much it would have cost if it hadn’t been increased?(Different method to other question)