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Babies born

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by anastasios1984 » Tue Feb 26, 2013 2:39 am
Each baby born at a certain hospital last week was either a single birth or one of a pair twins. If x is the number of babies born at the hospital last week, is x odd?

i) 33 single births
ii) 3 pairs of twins born

At present I do not have OA. However, this question was one among others I answered wrong at a previous mock test at my Gmat school

My line of reasoning was the below:

S - > single births
T - > twin births
X - > Total babies

S + 2T = X

i) 33 + 2T = X, which can be translated odd + even = odd, so i is SUFFICIENT

ii) S + 2*3 = X, NOT SUFFICIENT

so answer must be A, correct?
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Source: — Data Sufficiency |

by Anurag@Gurome » Tue Feb 26, 2013 4:37 am
anastasios1984 wrote:My line of reasoning was the below:
...
so answer must be A, correct?
Yes, your reasoning is correct.

However, this can solved without analyzing the statements as well.
We know that x = (Number of single births) + (Number of double births)
Now, number of double births will be always even.

Hence, x = EVEN + Something
If that something is even, x will be even
And if that something is odd, x will be odd

Hence, we just need to know whether the number of single births is even or odd.

The correct answer is A.
Anurag Mairal, Ph.D., MBA
GMAT Expert, Admissions and Career Guidance
Gurome, Inc.
1-800-566-4043 (USA)

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