Pick a Prime
  • A box contains five ping-pong balls, each with a number written on it. One ball has a one painted on it, one ball has a four, two of the balls are labeled with a seven and one ball has an eight. The balls are picked from the box one at a time without replacement and placed in the order they are drawn, from left to right, to create a five-digit number. What is the probability that the five-digit number is a composite number (not prime)?

Answer:    
  Please enter a numerical answer
(ex. 1000 or 2.033) and click GO.		    

Contest problems and answers provided by:

David Rock
rock_david@colstate.edu
Columbus State University

Doug Brumbaugh
brumbad@pegasus.cc.ucf.edu
University of Central Florida