Finding Median for Grouped Data When Class Intervals Are Given
Find the Medi...
Question
Find the Median from the following table-
Class Interval
0−20
20−40
40−60
60−80
80−100
Frequency
10
17
26
22
15
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Solution
Class Interval
Frequency (f)
Cumulative Frequency (C.F.)
0−20
10
10
20−40
17
27
40−60
26
53
60−80
22
75
80−100
15
90
∑f=N=90
Here N=90 Mid−point=N2=902=45 45th term is in the cumulative frequency 53. Median class is 40−60. here l1=40, l2=60, f=26, C=27 Md=l1+(N2−C)f(l2−l1) =40+⎛⎜
⎜
⎜⎝902−2726⎞⎟
⎟
⎟⎠(60−40) =40+(45−27)26×20 =40+1826×20 =40+18026 =40+13.84 =53.84 Thus, the median =53.84.