You have 13 socks of red colour, 5 socks of blue colour ,8 socks of green colour and 10 socks of yellow colour. What is the minimum number of socks needed to ensure you have atleast 3 socks of different colour. You draw socks at random.
I think you have to look at the worst case scenario
You COULD draw 13 red in a row, then 10 yellow in a row..... before drawing a third color : green or blue
so to ENSURE three clolors you will need to draw 13 + 10 + 1 = 24 draws
If this question was assigned to you your learning about the pigen hole principle.
You have to look at the worst case to ensure that you will get it.
If your really unlucky, you might get 10 yellow socks in a row and 13 red socks (soxs) in a row.
Then, it is certain that you will get an either GREEN SOCK, or YELLOW SOCK so we add 1.
10 + 13 + 1 = 24
Red Sox pun not intended but definitely appreciated...