Last updated at Jan. 27, 2020 by Teachoo

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Ex 1.1, 1 Which of the following are sets? Justify our answer. (i) The collection of all months of a year beginning with the letter J. We can count the months of the year beginning with J. (January, June, July) This cannot be changed. Thus, it is well defined. Thus, this is a set Ex 1.1, 1 Which of the following are sets? Justify our answer. (ii) The collection of ten most talented writers of India. As collection of ten most talented writers of India may vary from person to person. So, it is not well defined. Thus, this is a not a set Ex 1.1, 1 Which of the following are sets? Justify our answer. (iii) A team of eleven best–cricket batsmen of the world. As team of eleven best cricket batsmen of the world may vary from person to person. It is not well defined. Thus, this is a not a set Ex 1.1, 1 Which of the following are sets? Justify our answer. (iv) The collection of all boys in your class. As the collection of all boys in our class is known and can be counted (well defined) Thus, this is a set Ex 1.1, 1 Which of the following are sets? Justify our answer. (v) The collection of all natural numbers less than 100. Natural numbers = 1, 2, 3, 4, 5,6, 7,……….. Natural numbers less than 100 = 1, 2, 3, 4, 5,……98, 99, 100 As the collection of all natural numbers less than 100 is known and can be counted (well–defined) Thus, this is a set Ex 1.1, 1 Which of the following are sets? Justify our answer. (vi) A collection of novels written by the writer Munshi Prem Chand. As the collection of novels written by the writer Munshi Prem Chand is known and can be counted (well–defined) Thus, this is a set Ex 1.1, 1 Which of the following are sets? Justify our answer. (vii) The collection of all even integers. As the collection of all even integers is known and can be counted (well–defined) Thus, this is a set Ex 1.1, 1 Which of the following are sets? Justify our answer. (viii) The collection of questions in this Chapter. As the collection of questions in this chapter is known and can be counted (well–defined) Thus, this is a set Ex 1.1, 1 Which of the following are sets? Justify our answer. (ix) A collection of most dangerous animals of the world. As collection of most dangerous animals of the world may vary from person to person. So, it is not well defined. Thus, this is a not a set

About the Author

Davneet Singh

Davneet Singh is a graduate from Indian Institute of Technology, Kanpur. He has been teaching from the past 10 years. He provides courses for Maths and Science at Teachoo.