November 26 – December 3, 2010


A teacher announces that a test will be given on one of the five days of next week, but tells the class, "You will not know which day it is until you are informed at 8 am of your 1pm test that day".
Which day will be the exam given?

Submit your solution to .


The winner of this week's Challenge Problem receives a gift certificate for Baskin Robbins Ice Cream!


The Challenge Problem is posted every Friday in the afternoon (every other Friday over the summer). Solutions can be submitted until noon of the next Friday. Anyone may participate. The winner is drawn from the pool of correct solutions, with preference given to solutions that are better than others (for instance, an exact result over a floating point result, etc.); to undergraduate students over graduate students over faculty; and to people who have not won a prize.

For questions, comments, or suggestions for future challenge problems, or to be added/removed from the email list: please email .

The challenge problem is maintained by Mauricio Duarte, Sudip Paul and Erik Slivken.