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?
( 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.
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
Last edited by OzMark (2013-06-12 01:10:28)