106I'll give some hints for part (a), and part (b) is simply 1-P(a) (because they are complementary events)
If ram starts, he can win if:
1. he gets 6 first time
2. no 6 first time, sam doesn't get 6, ram gets 6.
3. no 6 for first 2 throws (for each) , ram gets 6 for his 3rd throw
4. no 6 for first 3 throws (each), 6 for ram's 4th throw.
5. ...
6. ...
7. ...
Calculate the probability for 1, 2, 3, 4 ,5, ...
and the required probability is the sum of these individual cases.
You should notice that the sum will be in geometric progression and then apply the infinite sum formula to get the probability.
