Video on Percentages
Introduction to Percentages
Q1)
16% of 80
= 16/100 x 80
= 12 4/5
Q2)
7 1/2% of 125
= 7.5/100
= 44.5
Q3)
210% of 300
= 210/100 x 300
= 630
Decreasing and Increasing by a Percentage
How to Increase:
Start by making a statement saying the percentage of the amount
- eg: Increase $20 by 10%
- 110% of $20 (we do 110% because we are finding 110% of $20[not just 10% because that would be decreasing])
Then convert this statement into a fraction over 100
- eg: Increase $20 by 10%
- 110% of $20 = 110/100 x 20
Then solve it using a calculator!
How to Decrease:
Start by making a statement saying the percentage of the amount
- eg: Decrease $20 by 10%
- 90% of $20 (we do 90% because we are finding 90% of $20[not just 10% because that would be decreasing by to much & not 110% because that would be increasing])
Then convert this statement into a fraction over 100
- eg: Decrease $20 by 10%
- 90% of $20 = 90/100 x 20
Then solve it using a calculator!
Review Sheet Answers
1. 3x
2. 0.65
3. 6
4. 45
5. 0.825
6. -85
7. 3/17
8. 6.25pm
9. 0
10. 3.62
11. 9xy + 2y
12. -2x2+22x-3
13. hemisphere
14. $24
15.10a^2y^2
16. 27/2500
17. 45
18. $142.50
19. 1705.04
20. 2xy(9x-5y)
21. -1
22. 179
23.4 & 2/25
24. -31
25. 12.25 pm
26. 3600
27. 66.24
28. 129.8cm
29. $104.89cm
30. 720
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