All about flooble | fun stuff | Get a free chatterbox | Free JavaScript | Avatars    
perplexus dot info

Home > Logic
Black and White (Posted on 2003-02-25) Difficulty: 2 of 5
Imagine that you have three boxes, one containing two black balls, one containing two white balls, and the third containing one black ball and one white ball.

The boxes were originally labelled for their contents (BB - WW - BW) but someone has inadvertently switched the labels so that now every box is incorrectly labelled.

Without looking inside, you are allowed to take one ball at a time out of any box that you wish, and by this process of sampling, you are to determine the contents of all three boxes.

What is the smallest number of drawings needed to do this?

See The Solution Submitted by Ravi Raja    
Rating: 3.1250 (8 votes)

Comments: ( Back to comment list | You must be logged in to post comments.)
Solution answer | Comment 24 of 25 |
I've seen this one before. You first have to take one from the box labelled "BW." Let's assume that the ball is black (it works either way). Since no box has the correct sign, this must be the "BB" box. Now, since no box has the correct label, you simply put the "BW" sign on the box labeled "WW" (since you can't leave the "WW" sign on the other box), and putthe "WW" sign on the remaining box.
  Posted by Stephen Ticsay on 2005-10-29 13:52:41
Please log in:
Login:
Password:
Remember me:
Sign up! | Forgot password


Search:
Search body:
Forums (0)
Newest Problems
Random Problem
FAQ | About This Site
Site Statistics
New Comments (12)
Unsolved Problems
Top Rated Problems
This month's top
Most Commented On

Chatterbox:
Copyright © 2002 - 2024 by Animus Pactum Consulting. All rights reserved. Privacy Information