I'm posting one puzzle, riddle, math, or statistical problem a day. Try to answer each one and post your answers in the comments section. I'll post the answer the next day. Even if you have the same answer as someone else, feel free to put up your answer, too!
Monday, October 12, 2009
Marbles in a Box, Marbles with a Fox
We have six white marbles, one red marble and four black marbles in a box. What would be the smallest number of marbles that we need to take out of the box to guarantee that we get three of the same color?
Assuming you can't look when you're choosing the marbles, I'd say 6. The worst case would be 1 red, 2 white, 2 black, then the sixth choice has to make a set of 3.
I was hoping to throw you off the trail by using the 'one marble' solution on Friday, but I guess I should have known better.
Six is the answer. The worst case scenario here is when you pull two white, two black, and one red marble. The sixth marble will be either white or black, giving you three of either.
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Assuming you can't look when you're choosing the marbles, I'd say 6. The worst case would be 1 red, 2 white, 2 black, then the sixth choice has to make a set of 3.
ReplyDeleteYup, 6.
ReplyDelete6
ReplyDelete6 is the least attempt to ensure dat we get atleast 3 marbles of same colour
ReplyDeleteI was hoping to throw you off the trail by using the 'one marble' solution on Friday, but I guess I should have known better.
ReplyDeleteSix is the answer. The worst case scenario here is when you pull two white, two black, and one red marble. The sixth marble will be either white or black, giving you three of either.