UPSC NDA Math Model Paper 4

Let 9 distinct observations are x1,x2,x3,x4,x5,x6,x7,x8, and x9 (Observations in ascending order)
Since n=9, then median term =(

9+1

2

)th=5th term.

Given: Median of a set of 9 distinct observations is 20.5
∴x5=20.5
Now, the last four observations are increased by 2.
So, New observations are x1,x2,x3,x4,x5,2x6,2x7,2x8, and 2x9
n=9, then median term =(

9+1

2

)th=5th term.
So, The median is 5th observation, which is remaining unchanged.
∴ There will be no change in the median.