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crawfy
Dec 13, 2013, 12:16 PM
From a standard pack of 52 playing cards 2 are selected at random
Find probability of choosing
a.ace of spades then 2 of diamonds (in that order)?0.25?
b.10 of clubs then any other 10?1/14?7.14%
c.a club and 3 of hearts (in any order)?27/52?
d.a red or black card?1?
e. a red then a black card?0.25?
f.a red ace, then a heart?7/13?

ebaines
Dec 13, 2013, 01:05 PM
Part (d) is corrcet, but none of the others are correct. Remember that for these problems carsd are selected without replacement. This changes the probabilities for the second card selected. For example problem (e) asks about a red card followed by a black - the probability of a red on the first draw is 26/52 or 1/2, but because that card is nort replaced in the deck before the next draw the probability of a black on the second draw (assuming you had a red on the first) is 26/51, because there are 26 black cards out of the 51 remaining. Hence the probability of drawing a red followed by a black card is (26/52)x(26/51) = 0.255.

Try these again and this time don't just post an answer but rather tell us how you got that answer.