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?
If it ain't broke, fix it until it is.
A number by itself is useful, but it is far more useful to know how accurate or certain that number is.
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)