1) The probability that a randomly selected person has high blood pressure (the event H) is P(H) = 0.4 and the probability that a randomly selected person is a runner (the event R) is P(R) = 0.5. The probability that a randomly selected person has high blood pressure and is a runner is 0.1. Find the probability that a randomly selected person has high blood pressure, given that he is a runner.
2)The probability that a randomly selected person has high blood pressure (the event H) is P(H) = 0.3 and the probability that a randomly selected person is a runner (the event R) is P(R) = 0.4. The probability that a randomly selected person has high blood pressure and is a runner is 0.1. Find the probability that a randomly selected person is a runner, given that he has high blood pressure.
3)The probability that a student correctly answers on the first try (the event A) is P(A) = 0.2. If the student answers incorrectly on the first try, the student is allowed a second try to correctly answer the question (the event B). The probability that the student answers correctly on the second try given that he answered incorrectly on the first try is 0.3. Find the probability that the student correctly answers the question on the first or second try.