# Playing cards and probability

• Oct 14th 2009, 10:54 AM
knightmaref5
Playing cards and probability

You are dealt two cards successively from a shuffled deck of 52 playing cards. Find the probability that both cards are black.
• Oct 14th 2009, 11:07 AM
my.life
hello dear

i think it is going 2 be :

P(BLACK)= 26 choose 2 / 52 chooce 2
in another way

26C2
______= 0.245
52C2

(( the 26 comes from 13 spades+13 club >>>as they called it "i think " :S :S ))

(Speechless)
• Oct 14th 2009, 01:46 PM
artvandalay11
Quote:

Originally Posted by CaptainBlack
Probability that the first is black is 13/52.

The probability that the second is black given that the first is black is 12/51

The answer you seek is the product of these (probably)

CB

I regret to inform you that half of the cards in a standard deck are black... spades and clubs$\displaystyle =13+13=26/52$
• Oct 14th 2009, 02:01 PM
artvandalay11
Quote:

Originally Posted by knightmaref5

You are dealt two cards successively from a shuffled deck of 52 playing cards. Find the probability that both cards are black.

What's the probability that the first card is black?

$\displaystyle \frac{26}{52}$

And now that you have 1 of the black cards, there are only 25 left out of 51, so the product of these is our answer

$\displaystyle \frac{26}{52}\cdot\frac{25}{51}$

whatever that comes out to be
• Oct 14th 2009, 02:04 PM
CaptainBlack
Quote:

Originally Posted by artvandalay11
I regret to inform you that half of the cards in a standard deck are black... spades and clubs$\displaystyle =13+13=26/52$

Oooppsss.. would you believe it was a deliberate error to check who was awake? (Angry)

CB