35. If y ≠ 3 and 2x/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.
(B) I only
(C) II only
(D) III only
(E) I and II
I dont know the OA ? So please help ?
My pick is (A)
Note that we are asked "which of the following MUST be true, not COULD be true. For such kind of questions if you can prove that a statement is NOT true
for one particular set of numbers, it will mean that this statement is not always true and hence not a correct answer.
So we should try to make the listed statements not true for some x and y (which satisfy y≠3 and 2x/y=prime>2).
I. x = y --> not necessarily true: x=3 and y=2 (2x/y=3=prime>2);
II. y=1 --> not necessarily true: x=3 and y=2 (2x/y=3=prime>2);
III. x and y are prime integers --> not necessarily true: x=10 and y=4 (2x/y=5=prime>2).
can't we go have another approach
by considering the options from 1st to 3rd
and see if 2x/y is not a prime no >2
I. x = y --> then 2x/y=2 which is not greater then 2 so can't be true
II. y=1 --> then 2x/y=2 which is also not greater then 2 so can't be true
III. x and y are prime integers --> then this value will be fractional only so cant be an INTEGER so can't be true
hence A is the answer
please enlighten me for this approach
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