Q.

Which of the following is a set

1 The collection of all the months of a year beginning with the letter J.  
2 The collection of ten most talented writers of India.  
3 A team of eleven best cricketers of the world.  
4 A collection of most dangerous animals of the world.  

Ans.

(1)

(1) The members of this collection are January, June and July. So, this collection is well defined and hence, it is a set.

(2) A writer may be most talented for one person and may not be for another person. So, this collection is not well defined. Hence, it is not a set.

(3) A batsman may be best for one person and may not be for another person. So, it is not well defined, hence it is not a set.

(4) The term most dangerous is not a clear term. An animal may be most dangerous to one person and may not be for another person. So, it is not well defined, hence it is not a set.