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Misinterpreting questions... for example:

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Misinterpreting questions... for example:

by nehap1986 » Sun Dec 20, 2009 12:36 pm
I was looking back through questions I recently missed on a GMAC practice exam and got stumped on one particular question...

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

Answers:

(81)

(54)

(36)

(27)

(18)


The correct answer is 27. I can see that if you do (9)x(6) =(54) and (54) is even so (54)=1/2m... m=27.

My question is what stops you from interpreting it as first finding (9) and then (6) and multiplying those answers by each other to get 36?
Thanks!!
Last edited by nehap1986 on Sun Dec 20, 2009 1:46 pm, edited 1 time in total.
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by Stuart@KaplanGMAT » Sun Dec 20, 2009 12:54 pm
nehap1986 wrote:I was looking back through questions I recently missed on a GMAC practice exam and got stumped on one particular question...

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

Answers:

81

54

36

27

18


The correct answer is 27. I can see that if you do (9)x(6) =(54) and (54) is even so (54)=1/2m... m=27.

My question is what stops you from interpreting it as first finding (9) and then (6) and multiplying those answers by each other to get 36?
Thanks!!
If the question is posted correctly, then there's no way that 27 is the correct answer - it should be 81.

By the rules of order of operations, the operation () applies to each number before you find the overall product. So, the solution should be:

(9) = 3*9 = 27
(6) = 6/2 = 3

(9)*(6) = 27*3 = 81
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by nehap1986 » Sun Dec 20, 2009 1:06 pm
I am sorry, I should clarify. The original question puts a box around m, not parenthesis. Looks more like [M] I guess. So I don't think it is an order of operations question. Other than that the question is verbatim. Is it possible the GMAC is wrong on this one?
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by Ian Stewart » Sun Dec 20, 2009 1:42 pm
The trick is, there's a box around each answer choice as well. There is no answer which reads '81'; it reads (81). The correct answer is (27), since by the definition of (27), (27) = 81.
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by nehap1986 » Sun Dec 20, 2009 1:45 pm
AH!

That is it, thank you so much.
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by Stuart@KaplanGMAT » Sun Dec 20, 2009 9:52 pm
Ian Stewart wrote:The trick is, there's a box around each answer choice as well. There is no answer which reads '81'; it reads (81). The correct answer is (27), since by the definition of (27), (27) = 81.
That would do it!
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