This Month's Contest:
PRIME TIME SEQUENCE

What number comes next in this “prime time” sequence?

6 15 35 77 143 221 323 ???

Choose from these five choices:

a. 393 b. 437 c. 529 d. 625 e. 820

Please email your solution to John Kador jkador@jkador.com using the subject line “Prime Time.” Deadline is January 25, 2011. Two responses will be selected to receive a signed copy of John Kador's How to Ace the Brainteaser Job Interview. Good luck!

Brainteaser:
A WEIGHTY PROBLEM

Your job is to weigh on a balance scale a few objects that are between 1 and 40 ounces. Counterweights are expensive and you're on a budget. You are allowed to buy one or more weights of only four denominations. Using weights of only these four denominations, you need to be able to weigh any weight from 1 to 40 ounces (whole number weights only, including 1 and 40 ounces). What are the four denominations and what are the least number of weights required in total?

SOLUTION TO PREVIOUS PUZZLER: WOULD YOU TAKE THIS BET?

To recap: Take an ordinary and well-shuffled deck of 52 cards. Deal out the top 13 cards face down. Here's the bet. If none of those 13 cards has a value above 9, then you win $1,000. If one or more of those 13 cards is ranked 9 or higher, then we win $1. The bet pays 1,000 to 1. Would you take this bet? Why or why not? The winning solution will show the probabilities either way.

We received only 14 entries. Readers offered a number of sophisticated calculations on both sides of the bet. But there was only one correct entry. Congratulations to Aaron J. Pettersen, NorthWest Financial Services, Inc., Indianapolis, IN.

Solution: The bet is a loser. Expert bridge players know this hand — one with no honor cards (cards above a 9) — as a Yarborough, after Charles Anderson Worsley, 2nd Earl of Yarborough (1809-1897), who is said to have made a small fortune using this bet. The odds of receiving such a hand are 1,827 to 1. Odds of even 1000:1 are for suckers.

SOLUTION TO A WEIGHTY PROBLEM: The least number of weights is two weights each of 1, 3, and 9 ounces, and one of 27 ounces.

You can balance any whole number of ounces between 1 and 40 with these seven weights.

John Kador is the author of 10 books. His latest book is Effective Apology: Mending Fences, Building Bridges, and Restoring Trust (Berrett-Koehler). www.effectiveapology.com