Given: The probability of getting head for each coin p1 = 0, p2 = 1/4, p3 = 1/2, p4 = 3/4, p5 =1
The question is
Suppose we toss the selected coin four times. Find p(Ci | B4) for each i = 1, . . . , 5. Here B4 means that the first head is obtained on the fourth toss.
What I have already calculated for other problems of this question: P(Get Head when a coin is tossed)= P(H)
P(H) = 1/2
P(C1|H) = 0, P(C2|H) = 1/10 , P(C3|H) = 1/5 , P(C4|H) = 3/10, P(C5|H) = 2/5
P(H2 | H1 ) = 3/4
Because of it`s head only at fourth try. I thought I need to use Geometric Distribution (P(x) = q^x-1 * p).
I calculated it and its P(B4) = 1/16. Here I use P(H) in the `p.
Then going back to original problem: P(C1 | B4) = P(C1 ∩ B4)/P(B4)
Then can you please tell me what P(C1 U B4) is?