JEE Main 2013 (Online) 25th AprilQuestion 1
In a set of $2n$ observations, half of them are equal to $a$ and the remaining half are equal to $-a$. If the standard deviation of all the observations is $2$; then the value of $|a|$ is :
Statistics
Solution
Mean is $0$, so $\sigma^2=a^2=4$ and $|a|=2$.