Question

Following are the marks obtained by 9 students in a mathematics test: 50, 69, 20, 33, 53, 39, 40, 65, 59

The mean deviation from the median is ______.

Options

• 9

• 10.5

• 12.67

• 14.76

Answer 1

The mean deviation from the median is 12.67.

Explanation:

Marks obtained are 50, 69, 20, 33, 53, 39, 40, 65 and 59

Let us write in ascending order

20, 33, 39, 40, 50, 53, 59, 65, 69.

Here n = 9

∴ Median = `(9 + 1)/2` th term = 5th term i.e. 50

∴ Median = 50

Now

`x_i`	`d_i = |x_i = Med|`
20	30
33	17
39	11
40	10
50	0
53	3
59	9
65	15
69	19
Total	`sumd_i` = 114

n = 9 and `sumd_i` = 144

∴ M.D. = `(sumd_i)/n`

= `114/9`

= 12.67