From a pack of 52 cards, two cards are drawn together at random. What is the probability of both the cards being kings ?

Let S be the sample space.
Then, n(S) = ⁵²C₂ = (52 x 51) / (2 x 1) = 1326.
Let E = Event of getting 2 kings out of 4.
n(E) = ⁴C₂ = 6.
P(E) = n(E) / n(S)
= 6/1326
= 1/221 .