Consider the trial on which 3 is first observed in successive rolls of a six-sided die. Let A be the event that 3 is observed on the first trial. Let B be the event that at least two trials are required to observe a 3. Assuming that each side has a probability of 1/6, find (a) P(A), (b) P(B),(c) P(A U B).

so (a) im guessing is just P(A)=1/6

(b) is at least two rolls? does that mean 1/12?

(c) P(A U B)= 1/6 + 1/12 - 0

Can some one please correct me if I am wrong?