UPSC NDA I 2021 Mathematics Solved Paper

Concept:
The mode of the n observation is the number that has the highest frequency.
Calculation:
Given scores 10,12,13,15,15,13,12,10,x and mode =15
Frequency of score ' 12′=2
Frequency of score ' 15′=2
But for mode to be 15,x
should be ' 15′