calculate mean deviation and its coefficient from median
INCOME-- 40-50 50-60 60-70 70-80 80-90 90-100
NO. -- 5 10 20 25 15 5
Median = size of 
Th item
= size of 
Th item
= size of 40th item
This corresponds to the class interval (70-80). Thus, this is the median class.
M = Median = 
+ 
× 10
= 70 + 
× 10
= 70 + 2 = 72
income | Mid value (m) | Frequency (f) | Cumulative frequency (f) | Deviation from median dm = | Fdm |
40-50 | 45 | 5 | 5 | 27 | 135 |
50-60 | 55 | 10 | 15 | 17 | 170 |
60-70 | 65 | 20 | 35 | 7 | 140 |
70-80 | 75 | 25 | 60 | 3 | 75 |
80-90 | 85 | 15 | 75 | 13 | 195 |
90-100 | 95 | 5 | 80 | 23 | 115 |
|
|
|
|
| ∑fdm = 830 |
Mean deviation = 
= 
= 10.375
Coefficient of mean deviation = 
= 
= 0.144