THIS MONTH'S CONTEST
BRAINTEASER #1: RED BULL DELIVERY
A brokerage has to deliver 3,000 cans of Red Bull to desperate colleagues in a retail office exactly 1,000 miles away. The firm hires a driver to transport the Red Bull; the driver can carry up to a maximum of 1,000 cans at a time. Moreover, the driver must consume one can for every mile he drives. Puzzle: What is the maximum number of cans of Red Bull that can be delivered?
BRAINTEASER #2: Colored triangles
This puzzle is from Mathcounts, a spelling bee-like mathematics competition for middle school students. Each circle at a vertex in the diagram to the right is colored red (R), yellow (Y) or blue (B). No two vertices of a drawn triangle have the same color. One triangle has been completed. What is the color of the vertex marked by the question mark?
Winners Of The Previous Puzzler
The previous contest, published in our December issue, asked readers to solve a puzzle involving Russian Roulette.
We received a record-breaking response to the puzzle about a game of imaginary Russian Roulette, which featured a six-chamber cylinder containing four empty chambers and two adjacent chambers with bullets. The first shot hits an empty chamber. The problem was, for the next shot, should you A) spin the cylinder again before pulling the trigger or B) pull the trigger without spinning the cylinder. Amazingly, responses were almost evenly split between the two possible solutions.
The correct answer is B) Do not spin the cylinder. Here's the explanation offered by one of the winners, Kevin Godchaux, Financial Advisor, Morgan Stanley, in San Luis Obispo, Calif.:
“The answer to this question comes easily to anyone who is a fan of the movie ‘The Deer Hunter.’ The solution is to fire again without spinning the barrel. Let's represent a six-shooter loaded with two bullets (B) in adjacent chambers and four empty chambers (E):
Cylinder Number: 1 2 3 4 5 6
Status of Cylinder: E E E E B B
Since the gun did not discharge after the first pull of the trigger, it can be assumed that the first spin landed on chambers one through four. That means that there is a 1/4 or 25-percent chance that the spin landed on the chamber directly before a bullet (chamber 4). There is a 3/4 or 75-percent chance that the spin landed on chambers one through three, allowing for another safe trigger pull. If you spin, you have a 2/3 or 66-percent chance of landing on one of the “safe” chambers. In summary, by not spinning you increase your odds of surviving by about 8.3 percent.”
Congratulations, and a signed book goes to each of the following winners: Scott Hillegass, State Farm Insurance, Bloomington, Ill. Kevin Godchaux, Financial Advisor, Morgan Stanley, San Luis Obispo, Calif.
Solution to Brainteaser #2: The answer is Y (or yellow). Though not every vertex must be filled in to get to the answer, we can determine the colors of each vertex by completing triangles as we move from left to right. The completed puzzle is shown below.
Please email your solution to [email protected] by March 15, using the subject line “February 2008 Puzzler.” We will select two winners from all correct entries, with extra consideration given to offbeat or elegant solutions. Winners will receive a signed copy of John Kador's How to Ace the Brainteaser Job Interview. Good luck.