So 15 lanes left, so 1/15= 6% chance that he chooses the lane next to you. 7 seconds of time, so 7/45=15% chance that he jumps in during those 7 seconds. So the overall probability is 1/15 * 7/45 = 15.5 % So the guy probably choose to jump in next to you, and is incredibly inconsiderate. Eventually both people will collide. so if it takes 90 seconds for one and 100 for the other, then if we multiply it by 10 we get that after 900 seconds for You and 1000 seconds for the guy you all will collide. So after 15 min you guys will collide. Then due to the time it takes for the accident the entire pattern will be messed up and the time to collide will change.