Hopefully I'm not giving anything away with this post (and Stewart Reuben is too busy at Hastings to notice), but here is the question on Swiss Pairings that was given as part of the arbiters exam in Dresden. NB I got the answer partly wrong (as did a number of other arbiters), and when I give the answer in a day or 2 (in the comments section) I'll explain the error in my thinking.
Part A: You have a 15 player tournament, the players being identified by their seeding numbers (1 through to 15). The top seed is White in round 1. What are the first round pairings?
The results of round 1 (in board order) are 1-0, 0.5-0.5, 1-0, 0-1, 1-0, 0.5-0.5, 1-0, 1-0
Part B: Player 13 withdraws from the event after round 1. What are the pairings for round 2?