Decimals and percentages · Ages 11–12

Percentage increase and decrease worksheet

Part of: Percentages

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Decimals and percentages · Ages 11–12

Numsprite
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Write each answer in the space. For word problems, show your working and write a sentence answer.

1.Increase 20 by 25%. The result is .
Answer:
2.Decrease 70 by 40%. The result is .
Answer:
3.Decrease 440 by 30%. The result is .
Answer:
4.Increase 250 by 20%. The result is .
Answer:
5.A number goes down from 200 to 100. By what percentage has it decreased?
Answer:
6.A number goes up from 240 to 336. By what percentage has it increased?
Answer:
7.A number goes up from 150 to 225. By what percentage has it increased?
Answer:
8.A number goes down from 160 to 152. By what percentage has it decreased?
Answer:
9.Increase 1100 by 25%, then decrease the result by 25%. The final result is .
Answer:

10.660 is decreased by 15%. Which calculation gives the result?
- A. 660 × 0.85
- B. 660 × 1.15
- C. 660 × 0.15
- D. 660 − 15
Choose the right answer
Answer:
11.A number goes up from 400 to 1000, so it has increased by 150%.
True or false?
Answer:
12.A number goes up from 220 to 880, so it has increased by 300%.
True or false?
Answer:

13.A minibus fare was $4. After a 10% fare rise, how much is the new fare?
Working:
Answer:
14.May's dad earns $37,000 a month, and this year he gets a 4% pay rise. How much more does he earn each month?
Working:
Answer:
15.A reservoir's water falls from 120 million cubic metres to 60 million cubic metres. By what percentage has it fallen?
Working:
Answer:
16.A cha chaan teng's set meal goes up from $36 to $45. By what percentage has the price risen?
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Answer:
17.A country park had 1800 visitors last month. This month the number fell by 5%. How many visitors came this month?
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Answer:
18.An online channel had 18000 subscribers last year. This year the number rose by 20%, and next year it is expected to rise by another 10%. How many subscribers are expected next year?
Working:
Answer:

Show the answers and working

Percentage increase and decrease worksheet: Answers and working

1. 25
After going up 25%, what percentage of the number is it? 100% + 25%.
Up 25% means 125% of the number: 20 × 125100 = 25.
2. 42
After going down 40%, what percentage of the number is left? 100% − 40%.
Down 40% leaves 60% of the number: 70 × 60100 = 42.
3. 308
After going down 30%, what percentage of the number is left? 100% − 30%.
Down 30% leaves 70% of the number: 440 × 70100 = 308.
4. 300
After going up 20%, what percentage of the number is it? 100% + 20%.
Up 20% means 120% of the number: 250 × 120100 = 300.
5. 50%
First find the decrease, 200 − 100, then what percentage of the original 200 that is.
It went down by 200 − 100 = 100; divide by the original: 100 ÷ 200 × 100% = 50%.
6. 40%
First find the increase, 336 − 240, then what percentage of the original 240 that is.
It went up by 336 − 240 = 96; divide by the original: 96 ÷ 240 × 100% = 40%.
7. 50%
First find the increase, 225 − 150, then what percentage of the original 150 that is.
It went up by 225 − 150 = 75; divide by the original: 75 ÷ 150 × 100% = 50%.
8. 5%
First find the decrease, 160 − 152, then what percentage of the original 160 that is.
It went down by 160 − 152 = 8; divide by the original: 8 ÷ 160 × 100% = 5%.
9. 1031.25
Up first: what is 1100 increased by 25%?
Then take 25% off that new number, not off 1100.
Up first: 1100 × 100 + 25100 = 1375; then down from 1375: 1375 × 100 − 25100 = 1031.25. The second 25% is taken from a bigger number, so it doesn't get back to 1100.

10. A. 660 × 0.85
After going down 15%, what percentage of the number is left? What is that as a decimal?
Down 15% leaves 100% − 15%, which is 0.85: 660 × 0.85.
11. True
Find the increase, divide it by the original 400 (not the new number), then compare with 150%.
It went up by 600; divide by the original 400: 600 ÷ 400 × 100% = 150%.
12. True
Find the increase, divide it by the original 220 (not the new number), then compare with 300%.
It went up by 660; divide by the original 220: 660 ÷ 220 × 100% = 300%.

Marking: 2 for the working, 1 for the answer, 1 for the sentence.

13. 4.4 dollars
After a 10% rise, what percentage of the old fare is the new one?
After the rise it is 110% of the old fare: 4 × 110100 = 4.4.
14. 1,480 dollars
The question asks how much more, not the new pay. Find 4% of 37000.
The rise is 4% of the old pay: 37000 × 4100 = 1480.
15. 50%
First find the fall, 120 − 60, then what percentage of the earlier 120 it is.
It fell by 120 − 60 = 60; on the amount before: 60 ÷ 120 × 100% = 50%.
16. 25%
First find the rise in dollars, 45 − 36, then what percentage of the old price 36 it is.
It rose by 45 − 36 = 9 dollars; on the old price: 9 ÷ 36 × 100% = 25%.
17. 1710 people
First find how many fewer came: 5% of 1800.
It fell by 1800 × 5100 = 90; 1800 − 90 = 1710.
18. 23760 subscribers
First find this year's subscribers: 18000 up 20%.
Next year's 10% is on this year's number, not on 18000.
This year: 18000 × 100 + 20100 = 21600; next year's rise is on this year's number: 21600 × 100 + 10100 = 23760.

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