A person has `n` friends. The minimum value of `n` so that a person can invite a different pairs of friends every day for four weeks in a row is _____.

A man has three friends. The number of ways he can invite one friend everyday for dinner on six successive nights so that no friend is invited more than three times is a. 640 b. 320 c. 420 d. 510

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

There are n distinct white and n distinct black ball. If the number of ways of arranging them in a row so that neighbouring balls are of different colors is 1152, then value of n is _________.

Find the number of integral value of n so that sinx(sinx+cosx)=n has at least one solution.

A man has 6 friends .how many ways can be invite one or more of them to a party?

Find the probability that the birthday of 7 persons will fall on 7 different days of the week assuming equal probability for each of these days.

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

Ten persons are arranged in a row . The number of ways of selecting four persons so that no two persons sitting next to each other's are selected is

A person writes a letter to four of his friends. He asks each one of them to copy the letter and mail to four different persons with instruction that they move the chain similarly. Assuming that the chain is not broken and that it costs 50 paise to mail one letter. Find the amount spent on the postage when 8th set of letter is mailed.

Prove that the sum of n number of terms of two different A.P. s can be same for only one value of ndot