Q1 of 23 Page 30

Which of the following are sets? Justify your answer.

(i) The collection of all the months of a year beginning with the letter “J”


(ii) The collection of ten most talented writers of India.


(iii) A team of eleven best cricket batsmen of the world.


(iv) The collection of all boys in your class.


(v) The collection of all even integers.

We know that a set is a collection of things that have something in common or follow a rule. Set notation uses brace {} with elements separated by commas.


(i) Collection of all months of a year beginning with the letter “J” = {January, June, July}


∴ This is a set.


(ii) Collection of ten most talented writers in India cannot be accurately defined.


∴ This is not a set.


(iii) Team of eleven best cricket batsmen of the world cannot be accurately defined.


∴ This is not a set.


(iv)Collection of boys in class = {Rohan, Sushant, Mohan, Rehan}


∴ This is a set.


(v) Collection of all even integers = {… -4, -2, 0, 2, 4, …}


∴ This is a set.


More from this chapter

All 23 →
2

If A = {0, 2, 4, 6}, B = {3, 5, 7} and C = {p, q, r} then fill the appropriate symbol, ∈or in the blanks.

(i) 0 ….. A (ii) 3 ……… C


(iii) 4 …… B (iv) 8 ……… A


(v) p ……. C (vi) 7 ……… B

3

Express the following statements using symbols.

(i) The elements ‘x’ does not belong to ‘A’.


(ii) ‘d’ is an element of the set ‘B’.


(iii) ‘1’ belongs to the set of Natural numbers N.


(iv) ‘8’ does not belong to the set of prime numbers P.

 4

State whether the following statements are true or false. Justify your answer

(i) 5 set of prime numbers


(ii) S = {5, 6, 7} implies 8 ∈S.


(iii) -5 W where ‘W’ is the set of whole numbers


(iv) Z where ‘Z’ is the set of integers.

 5

Write the following sets in roster form.

(i) B = {x : x is a natural number smaller than 6}


(ii) C = {x : x is a two-digit natural number such that the sum of its digits is 8}.


(iii) D = {x : x is a prime number which is a divisor of 60}.


(iv) E = {x : x is an alphabet in BETTER}.