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) =  $52C2$= 1326.

Let E = event of getting 2 kings out of 4.

n(E)  =  $\frac{52*51}{2*1}$= 6.

  $4C2$

=> $\frac{4*3}{2*1}$

$P\left(E\right)=\frac{n\left(E\right)}{n\left(S\right)}=\frac{6}{1326}=\frac{1}{221}$