atulmangal wrote:Is the integer n odd?
(1) n is divisible by 3.
(2) 2n is divisible by twice as many positive integers as n.
(1) n = 9 (ODD), and n = 12 (EVEN). Both of them are divisible by 3, so no definite answer.
So, (1) is NOT SUFFICIENT.
(2) If
n = 2 (EVEN), then 2n = 4, which is divisible by 1, 2, and 4. 2 is divisible by 1 and 2. Here 2n
does not have twice as many divisors as n.
If
n = 3 (ODD), then 2n = 6, which is divisible by 1, 2, 3, and 6. 3 is divisible by 1 and 3. Here, 2n has twice as many divisors as n.
If
n = 9 (ODD), then 2n = 18, which is divisible by 1, 2, 3, 6, 9 and 18. 3 is divisible by 1, 3, and 9. Here, 2n has twice as many divisors as n.
So, if n is ODD, then 2n will have twice as many divisors as n.
Hence, (2) is SUFFICIENT.
The correct answer is B.