A group of fifteen people consists of one pair of sisters, one set of three brothers and ten other people. The fifteen people are arranged randomly in a line.
Find the probability that the sisters are next to each other.[2]
Find the probability that the brothers are not all next to one another.[2]
Find the probability that the sisters are next to each other and the brothers are all next to one another.[2]
Find the probability that either the sisters are next to each other or the brothers are all next to one another or both.[2]
Instead the fifteen people are arranged in a circle.
Find the probability that the sisters are next to each other.[1]