revision

Created by: fhaidari97
Created on: 05-10-13 10:42

Percent' means 'out of 100'. If 90 per cent of the population owns a mobile phone, this means 90 out of every 100 people have one. The symbol '%' means per cent. Finding percentages A percentage is a fraction of 100. 30% (30 in each 100) as a frac

Find 40% of £50.First, write 40% as a fraction: 40% = 40/100 = 4/10 = 2/5 Now multiply by the quantity: 2/5 × 50 = £20.

1 of 6

With simple interest the amount of money borrowed remains fixed. For example £400 is borrowed for 3 years at an interest rate of 5% pa (pa means per annum, or each year). Interest for one year = 5% of £400 = (5/100 ) × 400 = £20 Interest for 3 y

Interest = P × R × T P (principal) is the amount borrowed. R is the rate of interest per year. T is the time in years.

2 of 6

Profit and loss People often buy something at one price, and sell it on for another - eg, when they are selling things at a car boot sale. If the selling price is greater than the buying price, a profit is made. If the selling price is less than th

Ajay is dealing in electrical goods. He buys a radio for £45 and sells it for £63. What is his percentage profit? Here the cost price is £45 and the selling price £63. The profit is £63 - £45 = £18 To calculate the percentage profit you have to fi

3 of 6

Charlotte buys a coat in a sale for £60. The original cost of the coat was £80. What is the percentage decrease?

The coat was bought for £60, and the original price was £80. The decrease is £80 - £60 = £20. To calculate the percentage decrease, divide the actual decrease by the original price and multiply by 100. 20 ÷ 80 x 100 = 25%.

4 of 6

To find a percentage of a quantity, turn the percentage into a decimal (divide by 100) and multiply the quantity by this. Here's an example: Find 55% of 230km. sums

The simple way to increase (or decrease) a quantity by a percentage is to find the percentage of the quantity that you want to increase (or decrease) it by and add it on (or take it off). For example: Increase £56 by 25%. 25% of £56 is £14 56 + 1

5 of 6

You can actually do it in one step instead of two! Here's how. 1. Work out what percentage you will have after your increase or decrease. 2. Change it to a decimal (divide by 100). 3. Multiply!

Decrease 900kg by 35%. After taking away 35% there will be 65% left. 65% as a decimal is 0.65 so 0.65 x 900 = 585 The answer is 585kg.

6 of 6

Other cards in this set