Question

If F(n) denotes the set of all divisors of a natural number n, what is the least value of y satisfying [F(20) ∩ F(16)] ⊂ F(y) ? 

(a) 2 

(b) 1 

(c) 4 

(d) 6

Answer 1

Correct option is (c) 4

Explanation :

F(n) = Set of all divisor of a natural number n. 

F(20) = {1,2,4,5,10} , F(16 ) = {1, 2 ,4 ,8 }

Now, F( 20) ∩ F(16) = {1,2,4} 

∴ F(y) = {1 ,2 ,4} 

= set of all divisor of a natural number y 

∴ y = 4