Primes/Exponents: If x, y, and z are integers greater than 1

I agree with adityanarula
it has to be A,

for x to be 5 it has to be prime, else 5^2*3^3=3*15^2 is also correct
so x could be 5 or 10 or 15.

Hmmm why did the discussion on this stop? Because according to the MGMAT, the OA is B!!!

abcdefg wrote:Hmmm why did the discussion on this stop? Because according to the MGMAT, the OA is B!!!

Because the original post misstated statement (1) (in the OP, statement 1 tells us that z is prime; in the actual question, statement 1 tells us that y is prime), so the MGMAT explanation for statement 1 doesn't apply to this thread.

lol gotcha thanks stuart

For the original problem (where statement 1 states that y is prime rather than z is prime):

5^2 * z = 3 * x^y
Case 1) 5^2 * 3 = 3 * 5^2
Case 2) 5^2 * 3 = 3 * 25^1
Case 3) 5^2 * (3*5^2) = 3 * 25^2

If Y is prime (y>=2), then that rules out Case 2 but not Case 1 and Case 3. So (1) is insufficient.

If X is prime (x>=2), then that rules out Case 2 and Case 3, but not Case 1. So (2) is sufficient.

Answer is B.

Yes, the problem was incorrectly stated. But it's interesting to see how Z plays a role too. Thanks for the explanation for the problem twist, Stuart.

But if we were to use the incorrectly stated problem
1) z is prime (instead of y is prime as per the original question)
2) x is prime

Then wouldn't the answer be B anyway???

5^2 * z = 3 * x^y
Case 1) 5^2 * 3 = 3 * 5^2
Case 2) 5^2 * 3 = 3 * 25^1
Case 3) 5^2 * (3*5^2) = 3 * 25^2

If Z is prime (z>=2), then that rules out Case 3 but not Case 2 and Case 3. So (1) is insufficient.

If X is prime (x>=2), then that rules out Case 2 and Case 3, but not Case 1. So (2) is sufficient.

Answer is B, and not D? Please clarify. Thanks!

gkumar wrote:Yes, the problem was incorrectly stated. But it's interesting to see how Z plays a role too. Thanks for the explanation for the problem twist, Stuart.

But if we were to use the incorrectly stated problem
1) z is prime (instead of y is prime as per the original question)
2) x is prime

Then wouldn't the answer be B anyway???

5^2 * z = 3 * x^y
Case 1) 5^2 * 3 = 3 * 5^2
Case 2) 5^2 * 3 = 3 * 25^1
Case 3) 5^2 * (3*5^2) = 3 * 25^2

If Z is prime (z>=2), then that rules out Case 3 but not Case 2 and Case 3. So (1) is insufficient.

If X is prime (x>=2), then that rules out Case 2 and Case 3, but not Case 1. So (2) is sufficient.

Answer is B, and not D? Please clarify. Thanks!

Nope - the original question tells us that x, y and z are all greater than 1. In case 2 you have y=1, which is impossible; therefore, case 2 is also ruled out.

Ah, thanks! Facepalm for me! >_<