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Calculation of Median: Continuous series
Median = L + [(h/f)(N/2 - C)]
Where :
L = lower Limit of the median class
h = magnitude of the median class
f = frequency of the median class
C = cumulative frequency of the class preceding the
median class.
Q. 8. Compute median from the following data:
| Mid value |
Frequency |
Mid value |
Frequency |
| 115
|
6 |
165
|
60 |
| 125
|
25 |
175
|
38 |
| 135
|
48 |
185
|
22 |
| 145
|
72 |
195
|
3 |
| 155
|
116 |
|
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Solution.
| Class intervals
|
f |
Cumulative
frequency (cf) |
|
110-120 |
6 |
6 |
|
120-130 |
25
|
31
|
|
130-140 |
48
|
79
|
|
140-150 |
72
|
151
|
|
150-160 |
116
|
267
|
|
160-170 |
60
|
327
|
|
170-180 |
38
|
365
|
|
180-190 |
22
|
387
|
|
190-200 |
3 |
390
|
|
Total |
390
|
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N = 390
N/2 = 390/2 = 195th item.
Therefore, the median class is 150-160
L = 150, N/2 = 195, h = 10, f =116, C = 151
Median = 150 + [(10/116) X (195 - 151)] = 150 + 3.79
= 153.79.
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