[quote="Carcass"]How many ways to choose 3 socks from three different pairs of socks such that one pair of socks is selected?
Okay. This is a tricky problem. But here's a way:
There are 3C1 ways of choosing 1 out of 3 pairs.
For the 3rd sock, there are 4 ways (of the remaining 2 pairs).
So, total ways = 3C1 * 4 = 3 * 4 = 12.