probability

[sud21]

[Anurag@Gurome]

Prime numbers between 30 and 45, inclusive are 31, 37, 41, 43.
Total integers between 30 and 45, inclusive = 16
Prime numbers between 30 and 45, inclusive = 4
Composite numbers between 30 and 45, inclusive = 12
The possibility that at least one prime number is selected is (1 prime, 1 composite) or 2 primes
Therefore, probability that at least one prime number will be selected = (4C1 * 12C1)/16C2 + (4C2/16C2) = (4 * 12)/120 + 6/120 = 54/120 = [spoiler]9/20[/spoiler]

The correct answer is B.

[ranvijay87]

Probability that first no is non prime 12/16 = 3/4
Probability that second no is non prime = 12/16 = 3/4
probability that atleast one prime will be selected = 1 - (3/4 * 3/4) = 5/16.
Please tell me what am i doing wrong here.