1) Blue, yellow and red are 1, 2 and 4 respectively. Since 96 is 24 times that of 4, we need to buy 1× 24 = 24 blue balloons and 2× 24 = 48 yellow balloons.

2) It can be found that every 7 balloons are a group, and the remainder of 100 divided by 7 is 2, so it should be the second balloon color of each group, that is, yellow.