Find the number of ways in which the birthday of six different persons will fall in exactly two calendar months.

The probability that the birth days of six different persons will fall in exactly two calendar months is

Find the number of ways in which four persons can sit on six chairs.

The number of ways of painting the faces of a cube with six different colours is

There are 20 people among whom two are sisters. Find the number of ways in which we can arrange them around a circle so that there is exactly one person between the two sisters.

The probability that the birthdays of 6 girls will fall on 6 different calendar months of a year is

There are 10 different books in a shelf. The number of ways in which three books can be selected so that exactly two of them are consecutive is

2American men; 2British men; 2 Chinese men and one each of Dutch,Egyptial,French and German persons are to be seated for a round table conference.If the number of ways in which they can be ways in which they can be seated if exactly two pairs of persons of same nationality are together is p(6!), then find p.

Find the number of ways in which four particular persons A,B,C,D and six more persons can stand in a queue so that A always stands before B,B before and C before D.