A beaver's teeth and jaws are so powerful that a group can fell a tree 20 inches thick in 15 minutes, The beaver Olympics is coming up this summer, and Bart Beaver claims his family can fell a tree twice as fast as the average group of beavers. Betty Beaver claims her family can fell a tree triple that size in double the time of the average group of beavers. On the day of the competition, the beavers will be required to fell the following trees: Tree 1: 20 inches thick Tree 2: 60 inches thick Tree 3: 10 inches thick Based on Bart's and Betty's predictions, how much time will it take each beaver family to fell the trees, and who will be the gold medal winner?