Three CSMA/CD stations are contending for access the shared medium in order to transmit a frame. They use 1-persistent CSMA/CD with the binary exponential backoff algorithm after a collision. (Thus, when they see the channel is idle, all three of them try to transmit a frame and the inevitable collision ensues, causing the binary exponential backoff algorithm to kick in.) What is the probability that the contention ends exactly on round k (as a function of k, of course)? What is the mean number of rounds per contention period?