$A$ regular polygon of $n$ sides has $170$ diagonals,then $n$ is equal to

The total number of possible ways in which a person can go from $A(0,0)$ to $B(3,3)$ if he can travel only to the right or upward along the grid lines is:

If three vertices are chosen from the six vertices of a regular hexagon and joined to form a triangle,what is the probability that the triangle formed is an equilateral triangle?

Three of the six vertices of a regular hexagon are chosen at random. The probability that the triangle formed by these three vertices is equilateral is equal to

In how many ways can $5$ boys and $5$ girls stand in a row so that no two girls may be together?

The number of straight lines that can be formed by joining $8$ points on a circle is: