Question

Write the following sets in roster form: (i) A = { x : x is an integer and –3 < x < 7}. (ii) B = { x : x is a natural number less than 6}. (iii) C = { x : x is a two-digit natural number such that the sum of its digits is 8} (iv) D = { x : x is a prime number which is divisor of 60}. (v) E = The set of all letters in the word TRIGONOMETRY. (vi) F = The set of all letters in the word BETTER.

Answer 1

(i)

The given set is,

A={ x:x is an integer and −3<x<7 }

The integers that lie between −3 and 7 are −2,−1,0,1,2,3,4,5,6, so, the roster form of the given set is,

A={ −2,−1,0,−1,2,3,4,5,6 }

(ii)

The given set is,

B={ x:x is a natural number less than 6 }

The natural numbers less than 6 are 1,2,3,4,5, so, the roster form of the given set is,

B={ 1,2,3,4,5 }

(iii)

The given set is,

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

The two-digit natural numbers whose sum of the digits is 8 are 17,26,35,44,53,62,71,80, so, the roster form of the given set is,

C={ 17,26,35,44,53,62,71,80 }

(iv)

The given set is,

D={ x:x is a prime number which is divisor of 60 }

The prime numbers that are the divisor of 60 are 2,3,5, so, the roster form of the given set is,

D={ 2,3,5 }

(v)

The given set is,

E=The set of all letters in the word TRIGONOMETRY

The word TRIGONOMETRY contains 12 letters, out of which T, R and O are repeated twice, so, the roster form of the given set is,

E={ T,R,I,G,O,N,M,E,Y }

(vi)

The given set is,

F=The set of all the letters in the word BETTER

The word BETTER contains 6 letters, out of which T and E are repeated twice, so, the roster form of the given set is,

F={ B,E,T,R }