WealthManagement Magazine
The Puzzler #22

The Puzzler #22

Think you're smart? Try these brainteasers that recruiters use in actual job interviews.


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 your opponent wins $1. The odds on this bet are 1,000 to 1. Would you take this bet? Why or why not? The winning solution will show the probabilities either way.

This puzzle comes courtesy of Jeevan Sivasubramaniam, editor of the BK Communiqué, a fine newsletter from Berrett-Koehler Publishers that has a puzzler and more in every issue. Check out back issues and subscribe for free at http://www.bkconnection.com/newsletter/newsletters.asp

Please email your solution to John Kador [email protected] using the subject line “Would You Take This Bet?” Deadline is October 11, 2010. Two responses will be selected to receive a signed copy of John Kador's How to Ace the Brainteaser Job Interview. Good luck.


We will pay you $10 million to complete this task: write out the integers, using correct English spelling, starting with “one,” “two,” “three,” and so on. The first time you use the letter “C” the task is complete and you will collect $10 million. Will you accept this job? Assuming that it takes 10 seconds to write out each integer, how much time will you require to complete the assignment? What will be your earnings per hour for the task?


To recap: You are presented with two bowls each with 25 black balls and 25 white balls. Blindfolded, you must choose one of the bowls at random and then draw single ball from it. But prior to putting on your blindfold and making your selection, you are allowed to redistribute the balls in the two bowls. What is the best strategy to ensure you will pick a white ball?

We received over 100 entries and most of them got the right solution. The best strategy is to put a single white ball in one bowl and the remaining 99 balls in the other. Once you are blindfolded you have a 50/50 chance of choosing the bowl with the single white ball. If you chose the bowl with 99 balls than you still have a 49/99 chance of choosing a white ball. The combined probability of choosing a white ball is approximately 75%.

Congratulations to the winners: Christopher S. Opper, Financial Advisor, Regent Financial Group, Pittsford, NY; and Scott Gordon, State Farm, Advanced Planning and Sales Support, Bloomington, IL.

SOLUTION TO NUMBER COUNTING: It's worse than you thought. The first time a”C” occurs is the number “one octillion.” At 10 seconds per integer, this task will require 300 quintillion years. The effective rate of pay would be $1.14 × 10-18 per hour ($.000000000000000000114 per hour).

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

TAGS: Games
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