Probability distribution table help w/ Tree diag .Two values coming strangely.
I'm having a problem with a tree diagram and the subsequent prob.dist.table. Here's the question:
Every day Eduardo tries to phone his friend. Every time he phones there is a 50% chance that his friend will answer. If his friend answers, Eduardo does not phone again on that day. If his friend does not answer, Eduardo tries again in a few minutesí time. If his friend has not answered after 4 attempts, Eduardo does not try again on that day.
(i) Draw a tree diagram to illustrate this situation.
This is correct.
(ii) Let X be the number of unanswered phone calls made by Eduardo on a day. Copy and complete the table showing the probability distribution of X.
This is what I'm seeing seeing:
x 0 1 2 3 4
P(X=x) 1/2 1/2 1/4 1/8 1/16
But, this seems to be wrong. Once again, I have no clue as to why this is so.
Any help? (Speechless)