Two cards are drawn from a well-shuffled pack of 52 cards. Find the probability distribution of a number of kings. Also, compute the variance for the number of kings. [CBSE 2007]
Given : Two cards are drawn from a well-shuffled pack of 52 cards.
To find : probability distribution of the number of kings and variance (σ2)
Formula used :

Mean = E(X) = ![]()
Variance = E(X2) - ![]()
Mean = E(X) =
= x1P(x1) + x2P(x2) + x3P(x3)
Two cards are drawn from a well-shuffled pack of 52 cards.
Let X denote the number of kings in the two cards
There are 4 king cards present in a pack of well-shuffled pack of 52 cards.
P(0) =
=
= ![]()
P(1) =
=
= ![]()
P(2) =
=
= ![]()
The probability distribution table is as follows,

Mean = E(X) = 0(
) + 1(
) +2(
) = 0 +
+
=
= ![]()
Mean = E(X) = ![]()
=
= ![]()
E(X2) =
=
P(x1) +
P(x2) +
P(x3)
E(X2) =
(
) +
(
) +
(
) = 0 +
+
= ![]()
E(X2) = ![]()
Variance = E(X2) -
=
–
=
=
= ![]()
Variance = E(X2) -
= ![]()
The probability distribution table is as follows,

Variance = ![]()