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by akhilchopra » Mon Aug 12, 2013 2:08 am
I came across this question in GMAT-Prep and wasn't able to get the answer.

Q) for all positive M, M=3M when M is odd and M= (1/2)M when M is even, what is the value of 9*6?

Choices:
1)81
2)54
3)36
4)27

Correct Ans:- 27. Could you please help in understanding the question?
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Source: — Problem Solving |

by GMATGuruNY » Mon Aug 12, 2013 2:56 am
In the actual problem, the answer choices all include the function symbol:
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 - @59
C - @36
D - @27
E - @18
Since @m=3m when m is odd, @9 = 3*9 = 27.

Since @m=(1/2)m when m is even, @6 = (1/2)6 = 3.

Thus, @9 * @6 = 27*3 = 81.

Notice the @ symbol in the answer choices.
The correct answer must be the EQUIVALENT of 81.

Answer choice D: @27
Since @m=3m when m is odd, @27 = 3*27 = 81.

The correct answer is D.

Answer choice A is A TRAP.
Always beware of an answer choice that seems TOO EASY or TOO OBVIOUS.
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