John wants to go abroad by ship and return by air. He has a choice of 6 different ships to go and 4 airlines to return. In how many ways can he perform his journey ?

A man has 7 friends. In how many ways can he invite one or more of them to a party ?

A man has 6 friends. In how many ways can he invite one or more of his friends to a party ?

A man has 10 friends. In how many ways he can invite one or more of them to a party?

In an Examination, a candidate has to pass in each of the four subjects. In how many ways can he fail ?

A Student has to answer 10 questions, choosing at least 4 from each of part A and part B. If there are 6 questions in part A and 7 questions in part B, in how many ways can the student choose 10 questions?

A question paper has two parts: Part A and Part B. each part containing ten questions. If the student has to choose 8 questions form part A and 5 questions from part B. In how many ways can he choose the questions?

A boy has 3 library tickets and 8 books of his interest in the library. Of these 8, he does not want to borrow Mathematics Part II, unless Mathematics Part I is also borrowed. In how many ways can he choose the three books to be borrowed ?

A person wishes to make up as many different parties as he can out of his 16 friends such that each party consists of the same number of persons. How many friends should be invite ?

A person of mass 60 kg wants to lose 5 kg by going up and down a 10 m high stairs. Assume he burns twice as much fat while going up than coming down. If 1 kg of fat is burnt on expending 7000 kilo calories, how many times must he go up and down to reduce his weight by 5 kg?