Jim's solution, finding how many people are needed for the probability that no one shares a birthday exceeds 50% (or any other cutoff value), is the one typically presented to solve the birthday problem (Google "birthday problem probability" for more web sites than you will want to examine).
The problem gets trickier if the question is 3 shared birthdays. Anyone care to tackle this one? Claudia J. Stanny, Ph.D. Director, Center for University Teaching, Learning, and Assessment Associate Professor, Psychology University of West Florida Pensacola, FL 32514 - 5751 Phone: (850) 857-6355 or 473-7435 e-mail: [EMAIL PROTECTED] CUTLA Web Site: http://uwf.edu/cutla/ Personal Web Pages: http://uwf.edu/cstanny/website/index.htm -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Sent: Monday, September 17, 2007 12:47 PM To: Teaching in the Psychological Sciences (TIPS) Subject: [tips] odds of same birthday calculation Can someone tell me the formula for calculating the probability of two students in a class having the same exact birthdate? What about THREE in a class of 20? Thanks Annette Annette Kujawski Taylor, Ph.D. Professor of Psychology University of San Diego 5998 Alcala Park San Diego, CA 92110 619-260-4006 [EMAIL PROTECTED] --- ---
