Mathematics Problem Of the Week

Spring 2008

POW #8

Blackballed

An urn contains exactly 10 balls, all of which are white at the start of this experiment. At each trial a ball is drawn from the urn (at random) and, if it is white, a black ball is put into the urn in its place. If the ball drawn on any trial is black it is simply returned to the urn.

What is the fewest number of draws that would give at least a 50% chance of having an equal number of black and white balls in the urn?

Due Friday, March 28^th at Noon.

Solutions should be submitted to Dr. R. Lock's mailbox in the Math/CS/Stat office or sent via e-mail to rlock@stlawu.edu.