math
posted by sally on .
A drawer contains exactly 5 red socks, 8 blue socks, 10 while socks, 12 green socks , and 7 yellow socks. Find the least number of socks to be chosen which will guarantee that there will be at least seven socks of the same color.

there's no way to pick 7 red socks, so it's a trick question.

Well, I can't be sure I'm right, but here's how I look at it.
Red
Blue
White
Green
Yellow
Each of the above is a color to choose from.
There is one that doesn't contain what you need, but you still have to take it into account so let's put that in first.
Red 5
Blue
White
Green
Yellow
Now it could be any color set of at least seven, which denotes seven or more socks.(I've never heard of this problem accounting for half a sock and will not hear it now. Also that's inconsequential in this particular problem.)
Red 5
Blue 7
White 7
Green 7
Yellow 7
Now, let's add that up. (7*4)+5= 33.
You need to pick 33 socks to be sure you have at leas seven of the same color.
For anyone looking at Steve's answer, please note that if they explicitly asked for 5 blue socks, the question would be a trick question. However, since they have to be "of the same color" and not "blue", we can calculate for any other color taking into account that there are blue socks that don't meet the minimum.