In how many ways can 12 different books be equally distributed among three students?

How can we obtain different gases from air?

In how many ways can one post 3 letters in 5 post boxes?

In how many ways can 10 scrips be arranged, so that the best and the worst do not come together?

A group consists of 4 girls and 7 boys.Ion how many ways can a tean of 5 members be selected so that the team has at least one boy and one girl?

In how many ways can 5 prizes be awarded to 4 boys if each boy is eligible for any number of prizes?

How many tangents can a circle have?

In how many ways can the letters of the words FRACTION be arranged so that the three vowels are never together?

In how many different ways can one invite 3 or more of his 6 friends?

In how many ways can a selection of 4 be made from 10 persons such that one particular person is always included