UPSC NDA Math Model Paper 7

Here data 3, 10, 10, 4, 7, 10, 5, 7
Number of observations = 8
Mean = (3 + 10 + 10 + 4 + 7 + 10 + 5 + 7) / 8
= 56/8
= 7
Now, sum of deviations = |3 - 7| + |10 - 7| + |10 - 7| + |4 - 7| + |7 - 7| + |10 - 7| + |5 - 7| + |7 - 7|
= 4 + 3 + 3 + 3 + 0 + 3 + 2 + 0
= 18
Now, mean deviation = 18/8 = 2.25
Hence, option (2) is correct.