If y ≠ 3 and 3x/y is a prime integer greater than 2, which of the following must be true?
Ⅰ. x = y
Ⅱ. y = 1
Ⅲ. x and y are prime integers.

3x/y is prime
I x=y then definitely 3x/y is prime =3

II y=1 then 3x/y = 3x (which cannot be prime unless x=1)

III if x & y are prime then 3x/y will be prime only if x=y, otherwise it wont be a integer itself

so only I must be true here to ensure that 3x/y is prime

samir, 1 MUST NOT be true.

x = 7 and y = 3 will make 3x/y prime. So, answer will be NONE.

But Kajcha its given that y <> 3 in the Q

Hey Kajcha,
You are correct the ans should be A coz if x=y=0 then the ans would be undefined.

thanks a ton guys..!!

manasi,
for future posts please make sure you dont post the answer immediatley after the question,please wait for couple of responses !!