Question

If there are 1024 relations from a set A = {1, 2, 3, 4, 5} to a set B, then the number of elements in B is 

(1) 3 

(2) 2 

(3) 4 

(4) 6

Answer 1

(2) 2

n(A) = 5 

n(B) = x 

n(A x B) = 1024 = 2¹⁰ 

2^5x = 2¹⁰ 

⇒ 5x = 10 

⇒ x = 2