Question

The number of elements in set $A$ is

• A. 6
• B. 7
• C. 5
• D. None of these

Answer 1

Answer: (B)

(i) $2^{n(A)}-2^{m(B)}=$ prime number. Also, $2^{\text{m}(B)}$ must be odd.
(ii) If $2^{w(A)}-2^{w(B)}$ is prime, then $n(B)$ is always zero.
(iii) Find $n(A)$ by trial and error method.