here is the answers and all of them are posted after being solved
1a)75
1b)24
1c)50

2)1

3 A=11
ODD ONE IS D

4 this one is quite interesting
bill should bet $15 on sprinterB because jack has only $99 and the highest pay he would get from bet after bill takes sprinter B is sprinterF and by luck if jack wins he will have total $99+99x10/1=$1089 but still bill would have $ 1090 even after losing bet which is $1 more than jack. bill has 100 percent win if he bets $15 even if he loses the bet. and he will win $ 1000000 from aunt.