Question

If 2 cards are drawn from a deck of cards, how do you find P(heart or club)?

Answer 1

The above explains the probability of drawing a heart or club in one draw very well. Now let's move over to P(heart or club) when drawing two cards.

 

This is a bit more complicated. There are two possibilities:

(1) You've already drawn a 'right' at the first draw P(1stRight)=1/2

as explained above

 

(2) You didn't. P(1stWrong)=1/2

Then there are 51 cards left: 26 'rights' and 25 'wrongs'. Probability of getting a 'right' in the second draw P=26/51 multiply by the first being wrong.

So P(1stWrong,2ndRight)=1/2⋅26/51=26/102

 

You may add the probabilities of cases (1) and (2):

P(H or C) =51/102+26/102=77/102=0.7549 (two cards)

the probability is 77/102 or 0.7549