A biased die is such that P (4) = 1/10 and other scores being equally likely. The die is tossed twice. If X is the ‘number of fours seen’, find the variance of the random variable X.
Since, X= number of four seen
On tossing to die, X=0,1,2
Also, 
and 
So, 
Thus, we get following table 1207110331
∴Var(X)=E(X)2-[E(X)2] =X2P(x)-[XP(X)]2
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