Your question is Guaranteed Matching Pair in Socks. Take a moment with it on the right.
Talk me through your thinking if you like. When you're confident, submit your answer and I'll grade it like a real screen (7/10 or better passes).
You have a drawer with 20 black socks and 20 white socks. You pull socks out at random in the dark and cannot distinguish colors while drawing.
What is the minimum number of socks you must pull out to guarantee you have at least one matching pair?