There are three ways to represent fractions of numbers - fractions, decimals and percentages. Percentages are a part of everyday life and you'll need to be able to calculate increase and decreases in percentages if you ever want to understand interest rates or pay rises!
To calculate a percentage increase, first divide the percentage by 100 and then multiply by the original figure. So, to find a 5% increase on £800, first divide 5 by 100 (0.05) and then multiply by 800 to get 40. Add this to the original figure to get £840.
To calculate a percentage decrease, follow the same steps but this time subtract 40 from 800 to give an answer of £760.
Put your numbers hat on and practise with the following quiz increases and decreases in percentages. If you can get the full 100% in this quiz, you've cracked it!
1.
|
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 |
|
|
2.
|
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% |
|
|
3.
|
Due to severe weather, a polar bear colony goes from 328 bears to 246. What percentage decrease is this? |
|
[ ] |
20% |
[ ] |
22% |
[ ] |
25% |
[ ] |
26% |
|
|
4.
|
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% |
|
|
5.
|
What percentage of 68 is 10.2? |
|
[ ] |
15 |
[ ] |
17 |
[ ] |
17.5 |
[ ] |
20 |
|
|
6.
|
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 |
|
|
7.
|
Pete's hourly wage goes up from £7.20 to £7.56. What percentage increase is this? |
|
[ ] |
3% |
[ ] |
4% |
[ ] |
5% |
[ ] |
6% |
|
|
8.
|
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 |
|
|
9.
|
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% |
|
|
10.
|
What percentage is 8.5 of 68? |
|
[ ] |
12 |
[ ] |
12.5 |
[ ] |
13 |
[ ] |
13.5 |
|
|
1.
|
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 |
[x] |
2,007 |
|
|
2.
|
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% |
[x] |
47.8% |
|
|
3.
|
Due to severe weather, a polar bear colony goes from 328 bears to 246. What percentage decrease is this? |
|
[ ] |
20% |
[ ] |
22% |
[x] |
25% |
[ ] |
26% |
|
|
4.
|
Michelle bought a caravan for £13,500 and sold it two years later for £11,200. What is the percentage loss? |
|
[ ] |
13% |
[ ] |
14% |
[ ] |
15% |
[x] |
17% |
|
|
5.
|
What percentage of 68 is 10.2? |
|
[x] |
15 |
[ ] |
17 |
[ ] |
17.5 |
[ ] |
20 |
|
|
6.
|
A burger now costs £3.75 after a 3% reduction in price. What was the original price of the burger? |
|
[ ] |
£2.88 |
[ ] |
£3.17 |
[x] |
£3.87 |
[ ] |
£4.44 |
|
|
7.
|
Pete's hourly wage goes up from £7.20 to £7.56. What percentage increase is this? |
|
[ ] |
3% |
[ ] |
4% |
[x] |
5% |
[ ] |
6% |
|
|
8.
|
The price of a concert ticket is £33 after a 7% increase. What is the original price of the ticket? |
|
[x] |
£30.84 |
[ ] |
£31.11 |
[ ] |
£33.65 |
[ ] |
£34.86 |
|
|
9.
|
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% |
[x] |
91% |
|
|
10.
|
What percentage is 8.5 of 68? |
|
[ ] |
12 |
[x] |
12.5 |
[ ] |
13 |
[ ] |
13.5 |
|
|
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