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• http://www.youtube.com/watch?v=PIbludyFDcg
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I am learning to work out percentages of amounts.
%
Percentages are out of 100.
100
Tim got 18 out of 25 in a test and Scott got 45 out of 50 in a test. Who got the best result ?
We need to change the tests into percentages so that we can compare them.
Let’s start by changing Tim’s score (18 out of 25) into a percentage.
0 25 50 10075
18
X 4
X 4
72
25
18
100
72
Multiplying the numerator and denominator by 4 will give us an equivalent fraction out of 100
72%
Now we need to turn Scott’s score (45 out of 50 into a percentage).
0 25 50 10075
45
X 2
X 2
90
50
45
100
90
Multiplying the numerator and denominator by 2 will give us an equivalent fraction out of 100
90%
Tim scored 72% and Scott scored 90%. It is now easy to see that Scott got the best result.
Room 13 completed a maths test out of 40. Help the teacher convert some student scores into percentages.
0% 25% 50% 100%75%
400
If the test is out of 40. What would 50% be?
20
What would 25% be? Tip: 25% is half of a half.
10 30
What would 75% be? Tip: a half plus one quarter.
The number line above is called a double number line. You can see it is very helpful to imagine when converting scores into percentages.
Room 9 completed a science quiz which was out of 16. Help the teacher convert some student scores into percentages.
0% 25% 50% 100%75%
160
If the test is out of 16. What would 50% be?
8
What would 25% be? Tip: 25% is half of a half.
4 12
What would 75% be? Tip: a half plus one quarter.
What would a score of 2 out of 16 be as a percentage?
2
You can see that 2 is exactly halfway between 0 and 25%.
Half of 25% is 12.5%.
12.5%
Now try these questions on your own.
1)
2)
3)
4)
5)
Click again when you have worked out all your answers.
Need some more practise? Try pg34 & 35 of Teacher Tools Fractions, Decimals and Percentages Book Numeracy resources
6)
7)
8)
9)
10)
25%
50%
50%
25%
20%
33%
20%
48%
150%
75%
Change these fractions into percentages
24
6
16
8
48
24
32
8
10
2
27
9
25
5
25
12
6
9
16
12