A box contains 20 black, 22 white, and 24 red socks. If a person draws socks at random one by one without looking, what is the minimum number of socks she must pick to be certain of having at least one pair of black socks?

Correct option is D

Solution:
To be certain of at least one pair of black socks, consider the worst case.
First, the person may pick all non-black socks:
· White socks = 22
· Red socks = 24 Total non-black socks = 46
After picking 46 socks, it is still possible that no black sock has been picked.
Now:
· 47th sock → first black sock (only one, no pair yet)
· 48th sock → second black sock (pair completed)
So, minimum socks required = 48
Correct answer:
(d) 48