CHAPTER 11:
PERCENTAGES
11.2:
Comparing Different Quantities
Ø
EXPLANATION:
·
You
will often need to compare groups that are different sizes
·
à Suppose that, in 1 school, 85 students took an exam &
59 passed. In another school, 237 students took an exam & 147 passed.
Which school did better?
·
It
is hard to say because each school had a different number of students.
·
The
worked example below shows how to use percentages to help to answer
questions like this.
Ø
EXAMPLE:
In school A, 85 students took a
mathematics exam and 59 passed
In school B, 237 students took
a mathematics exam and 147 passed.
Which school had a better pass rate?
ü
59 out of 85 =
59 : 85 = 69%
ü
147 out of 237
= 147 : 237 = 62%
è
The pass rate in school B is
better by 7 percentage points.
There were 425 girls
& 381 boys in a school. 31 girls & 48 boys are overweight.
Work out:
1.
The percentage of the girls that are overweight.
à 31 out
of 425 = 7.3%
2.
The percentage of all the students that are overweight.
è
79 out
of 806 = 9.8%
|
|
Smoker
|
Non-smoker
|
Total
|
|
Men
|
12
|
64
|
76
|
|
Women
|
9
|
32
|
41
|
a. What percentage of men are smokers?
ü
12 out of 76= 12 : 76 = 15.8%
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