1. Find missing frequency from the following data
-9,-4,a,5,8,11 and Median=2

Solution:
Here `-9,-4,a,5,8,11`

`M = (text{value of } (n/2)^(th) text{ observation} + text{value of } (n/2 + 1)^(th) text{ observation})/2`

`2 = (text{value of } (6/2)^(th) text{ observation} + text{value of } (6/2 + 1)^(th) text{ observation})/2`

`2 = (text{value of } 3^(rd) text{ observation} + text{value of } 4^(th) text{ observation})/2`

`2 = (a + 5)/2`

`4 = a + 5`

`a = 4 - 5`

`a = -1`