Two cards are drawn successively with replacement from a well-shuffled pack of 52 cards. Find the probability distribution of the number of kings.

Note: While reading this question you might have observed that cards are being drawn successively and sometimes in other question you might have get cards are drawn simultaneously


You have to be careful regarding these two words while solving the question. Both have a different meaning.


E.g.:-


When you draw 3 cards out of 52 simultaneously, then total no of ways of drawing is simply 52C3 = 22100. You draw 3 cards at a time.


When you draw 3 cards out of 52 successively, then total no of ways of drawing is not simply 52C3, once you have drawn the first card, only 51 cards are remaining and so on. You are drawing only one card at a time


In such case total ways of drawing 3 cards = 52C1 × 51C1 × 50C1 = 132600


Hence both are entirely different. So Be cautious regarding it.


Let’s solve the problem now:


Note: In our problem, it is given that after every draw, we are replacing the card. So our sample space will not change


In a deck of 52 cards, there are 4 kings each of one suit respectively.


Let X be the random variable denoting the number of kings for an event when 2 cards are drawn successively.


X can take values 0, 1 or 2


P(X = 0) =


{As we have to select 1 card at a time such that no king is there so the first probability is 48/52 and as the drawn card is replaced, next time again probability is 48/52 }


Similarly, we proceed for other cases.


P(X = 1) =


{we might get a king in the first card or second card, so both probabilities are added}


Similarly,


P(X = 2) =


Now we have pi and xi.


Now we are ready to write the probability distribution for X:-


The following table gives probability distribution:



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