posted by Ashley on .
A multiple choice quiz contains five question. Each question has four answer choices. Michael is not prepared for the quiz and decides to guess for each question. What is the probability that Michael will get at least one question correct? What is the probability that Micheal will get all five questions correct? Could you show me how to work it out please.
If the events are independent, the probability of both/all events occurring is determined by multiplying the probabilities of the individual events.
"At least one" = one or more.
1/4 * (3/4)^4 = ? (one correct)
(1/4)^2 * (3/4)^3 = ? (2 correct)
(1/4)^3 * (3/4)^2 = ? (3 correct)
(1/4)^4 * 3/4 = ? (4 correct)
(1/4)^5 = ? (5 correct)
Either-or probabilities are found by adding the individual probabilities.