GMATPRep weird m

[ddo]

Hi,

Got his question which does not look difficult but is weird and I do not know how to approach it.

Any idea?

[amitabhprasad]

m = 3m when m is odd and
m = 1/2m when m is even
9*6 = 1/2*9*6*3 = 81
I think you got it right ?
what's OA

[awilhelm]

The answer should be D. 81 is the solution to the equation, but 81 is equal to answer choice D, not answer choice A, which would be equal to 81*3, or 243.

[amitabhprasad]

I see it ow how it should be D.
9*3 =27
1/2*6 = 3
27*3 = 81
since when odd we should divide by 3 to keep it inside the CAGE
So it should be 27 and not 81
Got stumped ...

[ddo]

Answer is 27. Thanks

[gaggleofgirls]

Don't worry too much about the 'box' it is just a notation for function.

Since 9 is odd, the function (9) = 3(9) = 27

Since 6 is even, the function (6) = 1/2 * 6 = 3

So the product of function (9) * function (3) = 3*27 = 81

So, what you know is that the function(x) = 81

There are two possible functions here and neither are dependent on the even or oddness of the answer (which is 81), they are dependent on the even or oddness of the x. So, just solve:

if X is odd, then function(x) = 3(x)
We know the function(x) = 81
81 = 3x
x = 27 This works, X is odd. But this might not be the only answer.

You can try to see if x is even
I x is even, then function(x) = x/2
We know the function(x) = 81 so
81 = x/2
x = 2*81, which = 162 so Function(162) also = 81

SO function(9) * function(6) = function(27)
AND function(9) * function(6) = function (162)

Which is why the wording of the question is not what does function(9) * function (6) = but Which of the following is equivalent to...

Only function(27) is a choice (function(162) is not).

Answer is D ( 27 in the box)

-Carrie