Page 392 - Math Smart - 7
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Solution
In order to answer the question, you need to find the modal class. There are
10 pupils with heights ranging between 170 cm to 174 cm. The modal class of this
data is 170 cm < h < 174 cm.
The mode is a particularly useful measure of central tendency when there is a
The mode is a good large number of values in the data set.
average when there are
For example, a shopkeeper or manufacturer may need to know which is the most
many identical values in
popular product so that they can make the best decisions in order to maximise
the data set.
their profit.
17.1.2 Finding the median
Another type of average is the median. Let us recall how we can find the median
of a set of data.
The annual salaries of seven employees are shown. The manager wants to use
the 'middle' value to represent the annual salaries of her employees. What is
the middle value?
What is the middle value?
Employee Annual Salary ($)
Is it a good representation
A 27 000
of what most of her
B 21 000
employees are getting?
C 23 000
D 28 000
E 30 000
F 25 000
G 29 000
hink and Share Let us rank the data. In this example, we can order the salaries from the lowest
to the highest annual salary:
$21 000, $23 000, $25 000, $27^000, $28 000, $29 000, $30 000
What if you have an even
number of data values in
the set?
The middle value of this set of
How do you find the ranked data is the 4'^^ value out
'middle' value? Is there a
of 7 values, which is $27 000.
middle value?
The middle value of a ranked data set is called the median.
388 UNIT 17 Data Handling
II
