In a n-sided regular polygon, the probability that the two diagonal chosen at random will intersect inside the polygon is

Three vertices are chosen randomly from the seven vertices of a regular 7 -sided polygon. The probability that they form the vertices of an isosceles triangle is

A polygon has 77 diagonals. The number of sides of the polygon is

Two thirds of students in a class are boys and rest girls.It is known that the probability of a girl getting a first grade is 0.85 and that of boys is 0.70. Find the probability that a student chosen at random will get first grade marks.

In a box containing 10 bulbs, 2 are defective. What is the probability that among 5 bulbs chosen at random , none is defective ?

What is the formula to find how many diagonals are there in a polygon with n sides?

If four vertices a regular octagon are chosen at random, then the probability that the quadrilateral formed by them is a rectangle is

In a box containing 10 bulbs, 2 are defective. What is the probability that among 5 bulbs chosen at random, none is defective?

A polygon has 54 diagonals. Number of sides of this polygon is