Percentages

Emma has £3200 in a savings account. After a year, the bank pays her interest increasing her balance to £3360. What percentage rate was applied to the account?

The interest earned was 3360-3200 = £160. As a percentage of the original amount this is 160/3200×100 = 5%

Xena earns £420 a week after a 5% rise. What was her pay before?

Xena had a 5% rise, so £420 is 105% of her original pay. To find 1% of her original earnings, divide £420 by 105. Multiply this by 100 to find her old pay: 1% of her original earnings = 420/105 = £4 Original earnings = £4 × 100 = £400

Express 25% as a fraction

1/4

On Freya's 15th birthday, she was 159 cm in height, having grown 6% since the year before. How tall was she the previous year?

159 cm is 106% of her old height, so 1% of her previous height is 159/106 = 1.5 Her previous height was therefore 1.5 × 100 = 150 cm.

Find 40% of 400

160

95% of people in my street have a car. There are 160 people in my street. How many do not have a car?

8