A regular polygon of 10 sides is constructed. In how many way can 3 vertices be selected so that no two vertices are consecutive?

In how many ways can 2 doors be selected from 3 doors ?

In how many ways can 5 girls and 3 boys be seated in a row so that no two boys are together?

In how many ways can 5 girls and 3 boys be seated in a row so that no two boys are together?

In how many ways can 5 girls and 3 boys be seated in a row so that no two boys are together?

In how many ways can 5 girls and 3 boys be seated in a row so that no two boys are together?

In how many ways 2 persons can be selected from 4 persons?

In how many ways can 7 boys and 2 girls be seated in a row so that two giirls are together ?

A regular polygon of 10 sides is constructed. Triangles are formed joining vertices of the polygon. Find the number of triangles (i) if two sides of trinangle coincide with the sides of polygon. (ii) if only one side of triangle coincide with the side of polygon.

In how many ways can 5 boys and 3 girls sit in a row so that no two girls are together ?

A regular polygon has 20 sides How many triangles can be drawn by using the vertices, but not using the sides?