Two cards are drawn successively with replacement from a well shuffled pack of 52 cards. Then mean of number of kings is

The distribution function $$F(X)$$ of discrete random variable $$X$$ is given by

Then $$\mathrm{P[X=4]+P[x=5]=}$$

First bag contains 3 red and 5 black balls and second bag contains 6 red and 4 black balls. A ball is drawn from each bag. The probability that one ball is red and the other is black, is

A fair coin is tossed 4 times. If $$X$$ is a random variable which indicates number of heads, then $$\mathrm{P}[\mathrm{X}<3]=$$