11. Find the mean deviation about median for the following data :
Marks | ||||||
Number of girls |
Marks |
Number of Girls |
Cumulative Frequency c.f. |
Mid Points |
||
0-10 | 6 | 6 | 5 | 22.85 | 137.1 |
10-20 | 8 | 14 | 15 | 12.85 | 102.8 |
20-30 | 14 | 28 | 25 | 2.85 | 39.9 |
30-40 | 16 | 44 | 35 | 7.15 | 114.4 |
40-50 | 4 | 48 | 45 | 17.15 | 68.6 |
50-60 | 2 | 50 | 55 | 27.15 | 54.3 |
|
|
=517.1 |
Now, N = 50, which is even.
The class interval containing or item is 20-30. Therefore, 20-30 is the median class.
We know,
Median
Here, l = 20, C = 14, f = 14, h = 10 and N = 50
Therefore, Median
Now, we calculate the absolute values of the deviations from median, and
= 517.1
Hence, the mean deviation about the median is 10.34