Four fair six-sided dice, each with faces marked \(1,2,3,4,5,6\), are thrown. Find the probability that the numbers shown on the four dice add up to 5 .
Four fair six-sided dice, each with faces marked \(1,2,3,4,5,6\), are thrown on 7 occasions. Find the probability that the numbers shown on the four dice add up to 5 on exactly 1 or 2 of the 7 occasions.
Sharik attempts a multiple choice revision question on-line. There are 3 suggested answers, one of which is correct. When Sharik chooses an answer the computer indicates whether the answer is right or wrong. Sharik first chooses one of the three suggested answers at random. If this answer is wrong he has a second try, choosing an answer at random from the remaining 2 . If this answer is also wrong Sharik then chooses the remaining answer, which must be correct.