probabilty problem

[sukh]

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

[vineeshp]

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