In how many ways can two distinct subsets of the set `A` of `k(kgeq2)` elements be selected so that they haves exactly two common elements?

In how many ways can two distinct subsets of the set A of k(k>=2) elements be selected so that they haves exactly two common elements?

How many subsets does a set with n distinct elements have ?

In how many ways 10 distinct objects can be placed in 3 different boxes so that exactly one box will be empty

The number of one element subset,the number of two element subsets and the number of three element subsets o fa set containing more than three elements are consecutive terms of an A.P.The number of elements in the set can be

In how many different ways can a set A of 3n elements be partitioned into 3 subsets of equal number of elements? The subsets P ,Q ,R form a partition if PuuQuuR=A ,PnnR=varphi,QnnR=varphi,RnnP=varphidot

How many subsets in all are there of a set containing 4 elements ?

The probability that two randomly selected subsets of the set {1, 2, 3, 4, 5} have exactly two elements in their intersection, is :

A set A has n elements.A subset P of A is selected at random.Returning the elements of P ,the set A is formed again and then a subset Q is selected from it.Find the probability that P and Q have no common element.