Published by:
CGP EDU Academic Team
Published on: August 13, 2026
If the mean and variance of the following data:
6,10,7,13,a,12,b,12
are 9 and 
respectively, then 
is equal to:
Text Solution
Verified by ExpertsThe correct answer is:
D
Mean 
60 + a + b = 72
a + b = 12
variance 
….(2)
From (1) (1)a 2 + b 2 + 2ab = 144
80 + 2ab = 144 ∴ 2ab = 64
(a − b) 2 = a 2 + b 2 − 2ab = 80 − 64 = 16
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