ferdousrakib wrote:
From a pack, two cards are drawn, the probability that either both are red or both are kings is?
a) 44/163
b) 55/213
c) 151/275
d) None
If this question is right, then it's D.
The probability = probability of both red + probability of both Kings - probability of both red kings. None of ABC matches the value.
For probability of both red: First time you draw, you have 26 red cards out of 52, and second time you have 25 red cards out of 51, so probability of both red is (26/52)*(25/51)
Similarly, for both kings, you have 4 kings out of 52 cards first time and 3 out of 51 second time, so probability of both kings is (4/52)*(3/51)
For both red kings, you have 2 red kings out of 52 first time and 1 out of 51 second time, so probability is (2/52)*(1/51)
So probability is (26*25+4*3-2)/(52*51)=0.249
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Yuan Liu, Creator of Gregory. Dartmouth Grad.For More GRE Math Resources