Jee Main
Statistics
JEE Main 2023 (Online) 31st January Evening Shift
MCQ+4 / -12023
Let the mean and standard deviation of marks of class A of 100 students be respectively 40 and $\alpha(>$
0 ), and the mean and standard deviation of marks of class $B$ of $n$ students be respectively 55 and 30
$-\alpha$. If the mean and variance of the marks of the combined class of $100+\mathrm{n}$ studants are
respectively 50 and 350 , then the sum of variances of classes $A$ and $B$ is :
0 ), and the mean and standard deviation of marks of class $B$ of $n$ students be respectively 55 and 30
$-\alpha$. If the mean and variance of the marks of the combined class of $100+\mathrm{n}$ studants are
respectively 50 and 350 , then the sum of variances of classes $A$ and $B$ is :