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When calculating increases or decreases of percentages, always divide by the original amount. Put your numbers hat on and practice with the following Math quiz on the subject. If you get 100% in this quiz, you've cracked it!

1.

Barbara bought a box of 35 pens for £40.25. She sold all the pens for £1.70 each. What was her percentage profit?

39.4%

40.7%

45.8%

47.8%

2.

Pete's hourly wage goes up from £7.20 to £7.56. What percentage increase is this?

3%

4%

5%

6%

The increase is 36p. To work out the percentage 0.36 / 7.2 = 0.05 = 5%

3.

Due to severe weather, a polar bear colony goes from 328 bears to 246. What percentage decrease is this?

20%

22%

25%

26%

Remember, the change is always compared with the original value

4.

The Green family bought a house five years ago for £97,000. They sell it for £185,000. What is their percentage profit (to the nearest 1%)?

81%

85%

89%

91%

5.

A burger now costs £3.75 after a 3% reduction in price. What was the original price of the burger?

£2.88

£3.17

£3.87

£4.44

6.

What percentage is 8.5 of 68?

12

12.5

13

13.5

7.

The price of a concert ticket is £33 after a 7% increase. What is the original price of the ticket?

£30.84

£31.11

£33.65

£34.86

8.

What percentage of 68 is 10.2?

15

17

17.5

20

9.

A beehive increases by 7% a day. Initially there are 1,250 bees. How many will there be after a week?

1,620

1,800

2,000

2,007

A calculator is helpful for this kind of calculation! This problem is an example of compound increase. Problems like this can be solved using the compound interest formula:

M = P( 1 + i )n

Here, M = the final number of bees; P = the initial number of bees; i = the percentage increase (if it is a decrease, it will be negative; n = the number of days (but it could be weeks/months/years or any time period, depending on the problem) and it is the POWER to which (1 + i) has to be raised. Plug in the numbers and do the calculation

M = P( 1 + i )n

Here, M = the final number of bees; P = the initial number of bees; i = the percentage increase (if it is a decrease, it will be negative; n = the number of days (but it could be weeks/months/years or any time period, depending on the problem) and it is the POWER to which (1 + i) has to be raised. Plug in the numbers and do the calculation

10.

Michelle bought a caravan for £13,500 and sold it two years later for £11,200. What is the percentage loss?

13%

14%

15%

17%