probabilty problem

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probabilty problem

by sukh » Sat Aug 06, 2011 8:12 am
Set consists of all prime integers less than 10. If two numbers are chosen form set at random, what is the probability that the product of these numbers will be greater than the product of the numbers which were not chosen? (A) 1/3 (B)2/3 (C) 1/2 (D) 7/10 (E) 4/5 answer c

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by vineeshp » Sat Aug 06, 2011 9:28 am
Set = {2,3,5,7}
Ways of choosing 2 from 4 = 4C2 = 6

Favorable cases = 7*3, 7*5, 5*3 = 3 of the 6 (try writing down others)

Hence probability = 3/6 = 1/2
Vineesh,
Just telling you what I know and think. I am not the expert. :)