This problem is from Problem Solving Strategies - Crossing the River with Dogs and Other Mathematical Adventures by Ken Johnson and Ted Herr.
I decided to draw a picture from the segment of 90 ft to 100 ft of the race (the wall where they turn around). I chose to start at 90 ft because both two and three go into 90 evenly, so neither Roo or Tigger are in the middle of a jump at that time.
Thus, at the 96 foot mark, both Roo and Tigger are at the same spot. But, at the 98 foot mark, Roo is about to jump to the 100 ft mark and Tigger is mid-jump en route to the 99 ft mark. So, when Roo jumps, he is at the 100 ft mark and ready to turn around, while Tigger is on the 102 ft mark and then waiting to turn back around.
I am having trouble trying to figure out how much Roo wins by then exactly. It's hard to tell from my picture, but I believe it would be 2 feet. Is that correct, or does Roo possibly win by more? Any help would be appreciated.