Math Problem of the Fortnight
Trick Or Treat
You go to a haloween party. At this party everyone is to bring a treat and think of a trick
to play on the guests. All of the treats are collected by the host and uniformly at random
distributed back out to the guests. If a guest gets the treat that they brought, they are
allowed to play their trick on everyone. What is the expected number of guests that will get
to play their trick?
For an additional challenge: What is the probably that there will be no tricks played?
The Problem of the Week is open to all undergraduate students, regardless of major. Submit
your written solution, along with your name and e-mail address, to the Math Department
office (Founders Hall Room 2006) by 2:00 p.m. on Friday, October 28, 2016. There is a prize
of your choice of a $10 gift certificate to either Komal or Barista’s for the best solution.
http://www.unk.edu/academics/math/problem-of-the-fortnight.php
Disclaimer: Trivial solutions, although valid, run the risk of not being the best solution.