Which of the following collections are sets? Justify your answer:

**(i)** A collection of all natural numbers less than 50.

**(ii)** The collection of good hockey players in India.

**(iii)** The collection of all the girls in your class.

**(iv)** The collection of all talented writers of India.

**(v)** The collection of difficult topics in Mathematics.

**(vi)** The collection of novels written by Munshi Prem Chand.

**(vii)** The collection of all questions of this chapter.

**(viii) **The collection of all months of a year beginning with the letter J.

**(ix) **A collection of most dangerous animals of the world.

**(x) **The collection of prime integers.

Asked by Aaryan | 1 year ago | 57

**(i)** It is a set. Since, collection of all natural numbers less than 50 forms a set as it is well defined.

**(ii)** It is not a set. Since, the term ‘good’ is not well defined.

**(iii)** It is a set. Since, a collection of all the girls in your class it is a definite quantity hence it is a set.

**(iv)** It is not a set. Since, the term ‘most’ is not well defined. A writer may be talented in the eye of one person, but he may not be talented in the eye of some other person.

**(v)** It is not a set. Since, the term ‘difficult’ is not well defined. A topic may be difficult for one person, but may not be difficult for another person.

**(vi)** It is a set. Since, a collection of novels written by Munshi Prem Chand it is a definite quantity hence it is a set.

**(vii)** It is a set. Since, a collection of all the questions in this chapter. It is a definite quantity hence it is a set.

**(viii)** It is a set. Since, a collection of all months of a year beginning with the letter J. It is a definite quantity hence it is a set.

**(ix)** It is not a set. Since, the term ‘most dangerous’ is not well defined. The notion of dangerous animals differs from person to person.

**(x)** It is a set. Since, a collection of prime integers. It is a definite quantity hence it is a set.

Find the symmetric difference A Δ B, when A = {1, 2, 3} and B = {3, 4, 5}.