1. The problem statement, all variables and given/known data A has an infinite supply of marbles numbered 1,2,3,... A places the marbles, two at a time and in numerical order, into an urn (i.e. first 1 and 2, then 3 and 4, etc.). Each time A puts two marbles, B reaches in and pulls on out. This process goes on forever. c) If B always removes marbles randomly (each marble in the urn equally likely to e removed), with what probability will marble number 1 remain in the urn forever? 2. Relevant equations 3. The attempt at a solution Here is what I did: 1,2 =>prob that 1 stays is 1/2 1,3,4 => prob that 1 stays is 2/3 1,3,4,6 =>prob that 1 stays is 3/4 until (n-1)/n so we need to multiply them all and we are left with 1/n so as n->inf, the probability that it happens is zero ? Is my answer correct ? Thanks, Roni.