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is b even

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by saege » Fri Aug 08, 2008 9:28 am
If a and b are integers, is b even?

(1) 3a + 4b is even
(2) 3a + 5b is even

(A) Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.
(B) Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient.
(C) BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient.
(D) EACH statement ALONE is sufficient.
(E) Statements (1) and (2) TOGETHER are NOT sufficient.


C
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Source: — Data Sufficiency |

by parallel_chase » Fri Aug 08, 2008 10:28 am
Always remember following cases

even + even = even
odd +odd= even
even +odd = odd
odd+even =odd

b is odd or even ?

Statement I

3a+4b=even

4b will always be even weather b is odd or even
3a will also be even, therefore a is even.

Therefore, insufficient.

Statement II

3a + 5b is even

if a is odd b will also be odd, if a is even b will also be even and vice versa.

Therefore, insufficient.

Statement I and II

if a is even, b has to even.

Hence Sufficient.

C is the answer.
Last edited by parallel_chase on Fri Aug 08, 2008 11:59 am, edited 1 time in total.
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by eccentric » Fri Aug 08, 2008 11:48 am
parallel_chase this was exactly the route i had chosen to reach to solution

I hope u wanted to say o+o=E

Regards,
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by parallel_chase » Fri Aug 08, 2008 11:58 am
eccentric wrote:parallel_chase this was exactly the route i had chosen to reach to solution

I hope u wanted to say o+o=E

Regards,
Yup, exactly. Odd + Odd = Even.
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tks

by saege » Sat Aug 09, 2008 2:44 am
tks
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