First part: We choose 3 socks because they will all be the same or two of them will be one color and other one will be another
Second part: We choose two socks. The probability will be 1:2 . We can take two blue, two black or two different.
Third part: The solution is actually the same as in the second part.
It is a quite interesting puzzle, and it was plessure to solve it
Solved by:Olga Burkatovskaya and Alexander Buldyaev