Finding Mode for Grouped Data When Class Intervals Are Given
Calculate the...
Question
Calculate the mode of the following data.
Size of item
10−15
15−20
20−25
25−30
30−35
35−40
40−45
45−50
No. of items
4
8
18
30
20
10
5
2
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Solution
Size of the item
f
10−15
4
15−20
8
20−25
18
25−30
30
30−35
20
35−40
10
40−45
5
45−50
2
Modal class is 25−30 since it has the maximum frequency. Lower limit of the modal class l=25 Frequency of the modal class f=30 Frequency of the preceding modal class f1=18 Frequency of the class reducing the modal class f2=20 Class width c=5 Mode =l+(f−f12f−f1−f2)×c =25+(30−1860−18−20)×5=25+12×522 =25+6022=25+2.73=27.73 Mode =27.73