Example 2
What is the probability that a second tail occurs on the 6th toss of a fair coin?
Answer
there are ways for a tail to occur in the first
the probability of the second tail, P(x=2) means that one of the first 5 is tails, and we get tails for the final one. That is, 5/64.
Example 3
A quiz given. each question requires a true, false or cannot tell responses. The quiz has 10 questions in it. a) what is probability that Fermin will get exactly 6 questions correct if he only guesses
Answer
P(x=6) =
b) what is probability that his first question he gets right is the third question?
Answer
c) what is the excepted number of correct questions that Fermin will guess?
Answer
p = 1/3 E(x) = n * p (10)(1/3) E(x) = 3.333333333
Example 4
standard 52 deck. if you draw a face card, win 10 cents. if you draw ace card, win 25 cents. if you draw anything else, you lose 5 cents.
This is not a probability distribution because there are multiple win conditions going on.
But the E(x) = (3/13)*10 + (1/13)*25 + (9/13) *(-5) = 1