Is z an odd integer?

[BTGmoderatorDC]

Is z an odd integer?

(1) z is divisible by 3.
(2) The square root of z is an integer divisible by 3.

Isn't statement 1 sufficient?

OA E

[ceilidh.erickson]

Try TESTING CASES here:

Is z an odd integer?

(1) z is divisible by 3.
If z = 9, then yes: z is odd.
If z = 6, then no: z is not odd.

We tested 2 values that both fit the statement, and we got one yes and one no. Insufficient.

(2) The square root of z is an integer divisible by 3.
If the square root of z is divisible by 3, then z must be a perfect square that is divisible by 3. Again, test cases that fit:
If z = 9, then yes: z is odd.
If z = 36, then no: z is not odd.
Insufficient.

Putting the statements together does not help, because we already know statement 1 in knowing statement 2. Therefore, the answer must be E.