math
posted by makeeda on .
a sock drawer has 2 blue pair, 4 white pairs, 4 black pair. what is the probability you will pick out a white pair or blue pair? you replace each pair after your pick
i think it 4/10 im not for sure

Do you pick two? If you are trying for a matched pair, why would you replace the first one?
There are a total of 20 socks. You can either pick white and then white, or blue and then blue. Add the two probabilities.
(8/20)^2 + (4/20)^2
= (2/5)^2 + (1/5)^2
= 5/25 = 1/5