Ten people are sitting around a round table. Three of them are chosen at random to give a presentation. What is the probability that at least two of the three chosen people were sitting in consecutive seats?
there are 10 ways that 3 consecutive people can be chosen.
There are 10* 6 ways that 2 (but not 3) consecustive people can be chosen
So that is 70 ways that at least 2 consecutive people are chosen.
There are 10C3 = 120 ways that any 3 people can be chosen
so maybe 70/120 ways.
That is my best guess.