Problem Contest – Problem of the Week – March 9, 2004
Adding two positive integers: Let S = {1,2,3,4,5,6,7,8,9} be the set of nonzero digits.
Yuqiu draws one digit at random and then replaces it. Emily then draws a digit at random. Sid adds the two results. What digit is most likely to be in the units position of the sum? What is its probability of arising in this way?
Submit written solution with justification to John Emerson, Warner 312, before 3:00 on Tuesday, March 16. Or leave them in the Warner mailroom.
Note: Join us at the weekly seminars, usually on Tuesday at 3:00 for refreshments.