The answer for
1) 3 socks
2) 5 socks
3) 1 pair of socks
Explanation:
1) In the second trial, you choose one color, you say black, first, and second, say blue. The third sock you're taking out now has two black or brown. Therefore, you must draw at least 3 socks to ensure that you have a single color pair..
2) You get black first.
You're pulling out brown, second.
You tear down charcoal, Thrid.
Second, you cut out charcoal. (one pair complete)
Second, you're only heading out. (2 pairs full) Thus, you have to take out at least 5 socks to guarantee two pairs in the same colour.
3) You want 1 pair of black socks
The worst case is: [ 5 blu ]
The 6th pick guarantees you will have 1 pair of black socks