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#1 2013-06-12 06:07:10

mom
Full Member

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card probability

what is the probability of getting either a black card or an ace in one draw from an ordinary deck of 52 cards?

I got 8/13
26/52 black cards + 4/52 aces=8/13

the answer that was marked correct is 7/13

What did I do wrong?

#2 2013-06-12 06:14:59

bobbym
Administrator

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Re: card probability

( 6 / 13 ) + ( 1 / 13 ) = ( 7 / 13 )

Can you see why?


In mathematics, you don't understand things. You just get used to them.
I have the result, but I do not yet know how to get it.
All physicists, and a good many quite respectable mathematicians are contemptuous about proof.

#3 2013-06-12 10:28:55

OzMark
Novice

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Re: card probability

There are
13 black spades (including the ace of spades),
13 black clubs (including the ace of clubs),
the ace of diamonds,
the ace of hearts,
= 13 + 13 + 1 + 1 =28
28/52 = 7/13

Thanks

Last edited by OzMark (2013-06-12 23:10:28)

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