Question

If B = {1, 3, 5, 7, 9}, the set-builder representation of B is _________.

• A. B = {x : x is a prime number less than 10}
• B. B = {x : x is an odd number less than 10}
• C. B = {x : x is an odd natural number}
• D. B = {x : x is an odd natural number less than 10}

Answer 1

The correct option is D

B = {x : x is an odd natural number less than 10}

B = {x : x is a prime number less than 10} is wrong as 1 and 9 are not prime numbers.

B = {x : x is an odd number less than 10} is wrong as the set of odd numbers less than 10 gives {-∞,- - - - -, -5, -3, -1, 1, 3, 5, 7, 9}.

B = {x : x is an odd natural number} is wrong as the set of odd natural numbers gives {1, 3, 5, 7, 9, 11, ........, ∞}.

$\Rightarrow$B = {x : x is an odd natural number less than 10} is the set builder representation of B = {1, 3, 5, 7, 9}.