### Monday February 28, 2005

**Speaker**: Kyle Petersen (Brandeis)

**Title**: A Dinner Party Problem

**Abstract**:
There is a dinner to be served to *n* people
around a circular table. There are *n* napkins,
exactly one between each of the place settings. The
guests come to sit at the table one at a time and in
random order. When a guest arrives, if there are
napkins on both sides of the place setting, he or she
will choose the napkin on the right with probability
1/2 and the napkin on the left with probability 1/2.
If the guest finds only one napkin available, he or
she will take that napkin. However, some unfortunate
guests may be faced with the prospect of going through
dinner without any napkin! How many guests do we
expect to be napkinless?