The mean of the numbers obtained on throwing a die having written 1 on three faces, 2 on two faces and 5 on one face is


Given: A die having written 1 on three faces, 2 on two faces and 5 on one face.

Let X be the random variable representing a number on given die.


Then X can take any value of 1, 2 or 5.


The total numbers is six.


Now


P(X = 1)


P(X = 2)


P(X = 5)


Hence, the required probability distribution is,


X



1



2



5



P(X)









Therefore Expectation of X E(X):





E(X) = 2


Hence, the correct answer is (B).

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