If 4 people are chosen at random, then find the probability that no two of them were born on the same day of the week

If 4 people are chosen at random,then the probability that exactly two of them have the same birthday and another two of them have another same birthday of a week is

What is the probability of two persons being born on the same day ?

Six married couples are locked in a room, If two people are chosen at random, then the probability that one is male and the other is a female is

If 4 squares are chosen at random on a chess board,the probability that they lie on a diagonal line is

A box contains 5 defective and 15 non -defective bulbs two bulbs are chosen at random . Find the probability that both the bulbs are non - defective .

Seven accidents occur in a week then what is the probability that they hapeen on the same day.

Three mangoes and three apples are kept in a box. if two fruits are chosen at random, find the probability that one is a mango and the other is an apple.