Question

A bag contains 2 white and 1 red ball. One ball is drawn at random and then put back in the box after noting its colour. The process is repeated again. If X denotes the number of red balls recorded in the two draws, describe X. 

Answer 1

Let the balls in the bag be denoted by W₁, W₂, R. Then

S = {W₁W₂, W₂W₁, W₂W₂, W₁R, W₂R, RW₂, RR}

Now for W∈ S

X(W) = Number of red balls

Therefore,