Problem of the Week 1163
Walk a Mile in My Shoes
Five pairs of shoes of different sizes are in a closet. In how many ways can five people reach in and each remove a left and right shoe, so that no one gets a proper pair of shoes?
Source: Sally Cockburn and Joshua Lesperance, "Deranged socks," Mathematics Magazine 86 (2013) 96-109.
© Copyright 2013 Stan Wagon. Reproduced with permission.