Let `S = {(1,2,3,.....,n) and f_n` be the number of those subsets of Swhich do not contain consecutive elementsof S, then

Let S={1,2,3......,9}. For k=1,2,.....5, let N_(k) be the number of subsets of S,each containing five elements out of which exactly k are odd.Then N_(1)+N_(2)+N_(3)+N_(4)+N_(5)=?210(b)252(c)125 (d) 126

Let S={1,2,3, . . .,n} . If X denotes the set of all subsets of S containing exactly two elements, then the value of sum_(A in X) (min. A) is given by

Let S={1,2,3, . . .,n} . If X denotes the set of all subsets of S containing exactly two elements, then the value of sum_(A in X) (min. A) is given by

Let S={1,2,3, . . .,n} . If X denotes the set of all subsets of S containing exactly two elements, then the value of sum_(A in X) (min. A) is given by

Let S={1,2,3, . . .,n} . If X denotes the set of all subsets of S containing exactly two elements, then the value of sum_(A in X) (min. A) is given by

Let S={1,2,3, . . .,n} . If X denotes the set of all subsets of S containing exactly two elements, then the value of sum_(A in X) (min. A) is given by

A set contains 2n+1 elements.The number of subsets of this set containing more than n elements :

A set contains 2n+1 elements. The number of subsets of this set containing more than n elements :

A set contains 2n+1 elements. The number of subsets of this set containing more than n elements :

A set contains 2n+1 elements. The number of subsets of this set containing more than n elements :