Q4 of 23 Page 30

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.

We know that ∈ is read as “belongs to” and is read as “does not belong to”.


(i) False


Prime numbers = {2, 3, 5, 7, 11, …}


So, 5 ∈ set of prime numbers.


(ii) False


Given S = {5, 6, 7}


S does not include 8.


∴ 8 S


(iii) True


We know that W = {0, 1, 2, 3, 4 …}.


There are no negative integers.


∴ -5 W


(iv)False


We know that Z = {… -2, -1, 0, 1, 2 …}.


Integers do not include fractions or decimals.


∴ Z


More from this chapter

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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.

 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}.

 6

Write the following sets in the set-builder form.

(i) {3, 6, 9, 12}


(ii) {2, 4, 8, 16, 32}


(iii) {5, 25, 125, 625}


(iv) {1, 4, 9, 16, 25 … 100}