7.2a Range

Measures of Dispersion (Part 1)

7.2a Range

(A) Range of Ungrouped Data


Example 1:
Find the range for the set of data 2, 4, 7, 10, 13, 16 and 18.

Solution:
Range = largest value – smallest value
           = 18 – 2
           = 16


(B) Range of Grouped Data (with Class Interval)


Example 2:
The grouped frequency distribution was obtained from 100 students regarding the scores in their test shown as below.

Scores
Frequency
5 – 9
4
10 – 14
10
15 – 19
19
20 – 24
26
25 – 29
21
30 – 34
12
35 – 39
8

Find the range of the data.

Solution:
Range = midpoint of the  midpoint of the                    highest class           lowest class Range = 35 + 39 2 5 + 9 2             = 37 7             = 30

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