1A: 72
1B: 24
1C: 48

2: 1

3: 11; Odd one out: D

4: Solution: Bill has to bet $16 on sprinter B, that way he has 100% chance of winning.

Explanation: This one is tricky. In sports betting, 1-12 odds means if someone bets $1, he will win $12 and gets his bet back, so he'll end up with $13. Jack can only win, if he bets on the B sprinter with all of his money ($99). If B wins, he'll have $99+99*$12=$1287. If Bill bets on any other sprinter, Jack wins with this if B wins the race, because only one sprinter can win the race at the same time. So Bill must bet on B too to secure his win. $1287-$1105=$182. So Bill has to win more than this amount. $182/12=15,16. So $15 isn't enough, but $16 is. He will end with $1105+$192=$1297, and is going to win the $1,000,000.