posted by Melisa on .
There is a large jar of marbles, containing red, blue, yellow, black and white marbles. How many marbles must you draw(without looking) from the jar to be sure of getting at least three of one color?
I have a similar question with socks:
10 white, 6 black, how many drawn for one pair of white socks?
I will do the socks one ...
number of possible pairs = C(16,2) = 120
number of possible white pairs = C(10,2) = 45
so prob that both are white = 45/120 = 3/8
3 : 8 = 1 : 2.6667
Unless my thinking is way off, appr every third pair (I rounded it off) chosen would be a white pair.