• subscribe
August 19, 2005 12:00 AM

The Logical Puzzle

SQL Server Pro
InstantDoc ID #47011

Solution to August's Puzzle: Covering a Chessboard with Domino Tiles
In last month's puzzle, there was a chessboard with two missing corners that had been black. Using 32 domino tiles, each with a size of exactly two squares, you were asked whether it's possible to cover all the remaining 62 squares of the chessboard with domino tiles, without covering the missing corners. To solve this puzzle, you need to consider that because the two missing corners had been the same color (i.e., black), you have 32 white squares and 30 black squares left. Each domino tile covers exactly two squares—one black and one white. Any layout that you come up with will cover the same number of squares from each color. Therefore, it's impossible to completely cover all 62 remaining squares of the chessboard with domino tiles.

September's Puzzle: The Missing Buck
Three people arrive at a hotel and ask to share a room. The charge is $30, so each person chips in $10. Later on, the hotel receptionist finds out that he overcharged them by $5. Realizing that he can't evenly split $5 between the three guests, he pockets $2 and gives each guest $1 back. However, the receptionist finds it hard to sleep that night because the numbers don't seem to add up. Each guest eventually paid $9, and $9 x 3 + $2 = $29. Where's the missing buck?



ARTICLE TOOLS

Comments
  • DAN
    7 years ago
    Aug 27, 2005

    I'm commenting about the Missing Buck Logical Puzzle.
    I was sure fooled at first until I put my accounting hat on and wrote down the numbers trying to think of debits and credits and what values needed to be reconciled. I realized the missing buck is in the faulty logic (hense the name "Logical Puzzle" :) ).
    Bear with me while I try to explain it:
    The attempted mathematical proof makes it sound like "What was paid after discount" + "what was over-paid after discount" should equal "What was paid originally paid". That's not right.
    To re-calculate what was originally paid you add "What was paid after discount" ($9 * 3 people = $27) + the discount refunded to the 3 people ($1 * 3 people = $3), which comes to $30.
    When reconciling what was paid with the amount of change given, you have to reach the amount due, which is $25. They paid $27 (9 * 3), which is an overpayment of $2 (27 - 25), which the crooked receptionist kept for himself.
    The fair thing would have been to give $1.67 to two of them, and $1.66 to one them them and let the 3 guests decide who's going to be paying the extra penny.
    Better yet, if the 3 guests were all obstinate, and none of them was willing to pay an extra penny, the receptionist could have given them all $1.67, using a penny from his own pocket to keep them happy. Who knows, maybe the three guests would have been so pleased that they complemented the receptionist to his supervisor, contributing to a raise, earning him much more than $2 extra on every paycheck from then on out. This would allow him to both sleep well and prosper at the same time.
    Here's the moral of the story: A little greed is a heavy burden to carry, and a little generosity often multiplies and comes back to you!

You must log on before posting a comment.

Are you a new visitor? Register Here