Transcript Hot Shots - Teacher Tools

Hot Shots
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.
Multiplying the numerator and denominator by 4 will give us an equivalent
fraction out of 100
18
25
72
100
X4
72
18
0
25
50
75
100
72%
X4
Now we need to turn Scott’s score (45 out of 50 into a percentage).
Multiplying the numerator and denominator by 2 will give us an equivalent
fraction out of 100
45
50
45
0
25
90
100
X2
50
90
75
100
90%
X2
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.
If the test is out of 40. What would 50% be?
What would 25% be?
Tip: 25% is half of a half.
What would 75% be?
Tip: a half plus one quarter.
0
10
20
30
40
0%
25%
50%
75%
100%
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.
If the test is out of 16. What would 50% be?
What would 25% be?
Tip: 25% is half of a half.
What would 75% be?
Tip: a half plus one quarter.
What would a score of 2 out of 16 be as a percentage?
You can see that 2 is exactly halfway between 0 and 25%.
Half of 25% is 12.5%.
0
0%
2
4
12.5% 25%
8
12
16
50%
75%
100%
Now try these questions on your own.
Change these fractions into percentages
Click again when you have worked out all your answers.
9
6)
6
27
25%
1)
24
5
7)
8
50%
25
2)
16
12
8) 25
50%
3) 24
48
9
9)
8
25%
4)
6
32
33%
20%
48%
150%
2
75%
10) 12
20%
5)
16
10
Need some more practise? Try pg34 & 35 of Teacher Tools Fractions,
Decimals and Percentages Book Numeracy resources