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- Ian earns £420 a week after a 5% rise. What was his pay before?
Ian had a 5% rise, so £420 is 105% of his original pay.
To find 1% of his original earnings, divide £420 by 105.
Multiply this by 100 to find his old pay:
1% of his original earnings = 420/105 = £4
Original earnings = £4 × 100 = £400
- An Iyonix PC is sold for £1200 at a reduction of 20% on its recommended retail price. What was the computer's original price?
1200 is 80% of the original price, so 1% of the original cost would be 1200/80 = 15
So the original price would be 15 × 100 = £1500
- Kenny has £3200 in a savings account. After a year, the bank pays him interest increasing his 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%
- On my sister'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.
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