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Capthan
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Post subject: different values of m  Posted: Sun Jan 18, 2009 9:05 am |
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For all positive integers m, m*=3m when m is odd and m*=1/2m when m is even.
Which of the following is equivlant to 9*x6*?
A) 81*
B) 54*
C) 36*
D) 27*
E) 18*
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capthan
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Post subject: Posted: Mon Jan 19, 2009 6:41 am |
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This question is from GMAT prep; I am sorry, I posted it in the wrong place.
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nyhoosier
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Post subject: Posted: Sat Jan 24, 2009 5:31 pm |
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The answer is D) 27*
since 9 is odd, 9* =(3)(9) = 27
and 6 is even, 6* = (1/2)(6) = 3
notice that 6* =3 is the same as the "odd m" formula. Therefore 9*x6* is equivalent to 27*
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Guest
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Post subject: Is the answer “A” 81*? Posted: Sun Jan 25, 2009 12:26 pm |
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Is the answer “A” 81*?
We are told m* = 3m when m* is odd and m* = 1/2m when m* is even.
We need to know what 9* x 6* is equals?
So we just plug in 9 and 6 in the above provided info.
9 is odd and 6 is even so equation for this will look like this
(9x3) (6x1/2) = 27 x 3 = 81
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Hasan
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Post subject: Re: Is the answer “A” 81*? Posted: Sun Jan 25, 2009 3:02 pm |
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Anonymous wrote: Is the answer “A” 81*?
We are told m* = 3m when m* is odd and m* = 1/2m when m* is even.
We need to know what 9* x 6* is equals?
So we just plug in 9 and 6 in the above provided info.
9 is odd and 6 is even so equation for this will look like this
(9x3) (6x1/2) = 27 x 3 = 81
you are correct so far in your calculation, but if you observe the answer options given, the options are (A) 81* and not 81 hence this would be = 3 x 81.
So, the correct answer is (D) 27* = 3 x 27 = 81
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esledge
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Post subject: Posted: Sat Jan 31, 2009 11:16 pm |
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| ManhattanGMAT Staff |
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Posts: 901
Location: St. Louis, MO
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This is a sneaky problem, and I must admit that I fell for the same 81 trap in (A) the first time I saw the problem. It should be noted that the original GMATPrep problem notation is not of the form 2* but more like a "2 within a square" that I can't draw here. That made it even trickier, because it was all to easy to fail to "see" the squares around the numbers in the choices.
In retrospect, I noticed that the wording of the question is revealing: it says "Which of the following is equivalent to ..." NOT "which of the following is the value of ..." or "which of the following is ..."
The "equivalent to" is a hint that you must translate the answer choices, as well. 27* = 81.
_________________
Emily Sledge
Instructor
ManhattanGMAT
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RonPurewal
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Post subject: Re: Posted: Wed Feb 18, 2009 5:17 am |
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| ManhattanGMAT Staff |
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Posts: 7146
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esledge wrote: The "equivalent to" is a hint that you must translate the answer choices, as well. 27* = 81. awesome, yeah. nice catch. the gmat is INCREDIBLY specific about the way it writes its problems and answers. therefore, EVERY WORD of the problem statement should, ideally, carry some significance. read accordingly. but pay double and triple attention to any and all symbols that are present in the problem. symbols matter.
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EmilyJ
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Post subject: Re: different values of m Posted: Sun Feb 19, 2012 2:13 pm |
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Posts: 3
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What would this type of a problem be categorized as? Would it be a number properties type of question?
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jnelson0612
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Post subject: Re: different values of m Posted: Sun Feb 19, 2012 10:44 pm |
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| ManhattanGMAT Staff |
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Posts: 1857
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Hi Emily, this would be under the broad heading of Equations, Inequalities, and VICS (EIVs, Strategy Guide #3) and the subheading of Function questions.
_________________
Jamie Nelson
ManhattanGMAT Instructor
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