Problem of the Week #21

Thank you for participating the last Problem of the Week. We received quite a few submissions to #20, and the winner is Brendan Caseria, who provided the first solution; we would like to mention Russel Hart, Stephen Skapek, and Scott Goodson for providing more or less the same solutions.

After having a Calculus problem in #20, #21 is even more elementary:


Problem of the Week #20

Thank you for participating in the previous Problem of the Week! We received one correct solution from Nathan Hannon, who is our alumnus.

Our next challenge is the following differential calculus question.