Ten persons are arranged in a row. The number of ways of selecting four persons so that no two persons sitting next to each other are selected is

Ten persons are arranged in a row . The number of ways of selecting four persons so that no two persons sitting next to each other's are selected is

10 persons are sitting in a row. Find the number of ways of selecting two persons out of them who are sitting adjacent to each other

If n persons are sitting in a row, find the number of ways of selecting two persons, who are sitting adjacent to each other.

if n objects are arranged in a row then the number of ways of selecting three of these objects so that no two of them are next to each other is

20 persons are sitting in a particular arrangement around a circular table. Three persons are to be selected for leaders. The number of ways of selection of three persons such that no two were sitting adjacent to each other is a. 600 b. 900 c. 800 d. none of these