Need help on a GMAT problem

MonicaKhan wrote:For all positive integers m, m* = 3m, when m is odd and m* = (1/2)m when m is even. Which of the following is equivalent to 9* x 6*?

A) 81
B) 54
C) 36
D) 27
E) 18

I just can't figure this one out! The answer is D, but I don't understand why. Any help would be appreciated.

Whats the source for this problem ?

9* = 27 and 6* = 3. So, I'm not sure how it can be D

It was on one of my practice exams on the GMATPrep CD. SO bizaare!

For all positive integers m, m* = 3m, when m is odd and m* = (1/2)m when m is even. Which of the following is equivalent to 9* x 6*?

A) 81
B) 54
C) 36
D) 27
E) 18

9* (here m is odd) = 3*9=27
6* (here m is even) = 1/2*6=3
So answer = 27 times 3 = 81
Hence A

tricky one. Tha answer is 27. Not sure exactly one. One train of thought is 9*6 = 54 and therefore 54 * .5 equals 27. Any other thoughts?

Answer should be A

The question (or more precisely the answer choices) are not posted correctly.
See the screenshot, on how the question actually appears. This should make things clearer on why the answer choice is 27.

Good catch with that one II, its clear now

Can you guys lay out how you got to the answer? I want to confirm my work listed above. Thanks much.

The trick was in the answer choices. If you look at the answer choices that II posted, they are all 'boxed' just like M is in the main question.

In monicaKhan's original question '*' were used in place of the 'box', but the '*' should have been put next to all of the answer choices also, because they fall under the parameters of the function.

So all of us were getting '81' and not understanding how it was '27,' this is how:

9 is odd so it's-- 3(9)
6 is even so it--- 6/2

so 9*x6*=

3(9) x (6/2)=

27x 3=

81

Now, to get the correct answer apply the rules to the answer choices:

27* is 3(27)= 81...Answer choice (A) is really 81*, which would be equal to 243.

Choose D


Hope that helped

rros0770 wrote:The trick was in the answer choices. If you look at the answer choices that II posted, they are all 'boxed' just like M is in the main question.

In monicaKhan's original question '*' were used in place of the 'box', but the '*' should have been put next to all of the answer choices also, because they fall under the parameters of the function.

So all of us were getting '81' and not understanding how it was '27,' this is how:

9 is odd so it's-- 3(9)
6 is even so it--- 6/2

so 9*x6*=

3(9) x (6/2)=

27x 3=

81

Now, to get the correct answer apply the rules to the answer choices:

27* is 3(27)= 81...Answer choice (A) is really 81*, which would be equal to 243.

Choose D


Hope that helped

Great summary !
This is a tricky question ... and GMAC have many traps in this questions.
The key is to read the question carefully ... tough when you are under time pressure and stress. Question is asking "which is EQUIVALENT" ... this is the key part of the question.

Thanks. And its great when they give you this trickery on question 3!

What confuses me a bit is that they say when m (not boxed) is odd. But we are looking at boxed figures in the beginning (9 and 6)

bumpy bump

darn

tricky as heck this one
finally got it...thanks all!