Published by:
CGP EDU Academic Team
Published on: August 23, 2026
Let the mean and standard deviation of marks of class A of 100 students be respectively 40 and 
( 
, and the mean and standard deviation of marks of class B of 
students be respectively 55 and 30 
. If the mean and variance of the marks of the combined class of 
studants are respectively 50 and 350, then the sum of variances of classes 
and 
is :
Text Solution
Verified by ExpertsThe correct answer is:
D
Using formula of standard deviation
or 
if 
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