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

 Marks obtained by 9 students in Mathematics are: 

50, 69,20, 33, 53,39,40,65, 59
Let us rewrite the given data in ascending order.
20, 33, 39, 40, 50, 53, 59, 65, 69

$\text{ Here, }n=9\text{ [odd] }$

$\text{ Median }\left(M_e\right)=5\text{ th term }=50$

$\text{ M.D. }=\frac{114}{9}=12.67$