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Re: Number Property [#permalink]
21 Dec 2010, 00:29

2

This post received KUDOS

Expert's post

psirus wrote:

If m is an integer, is m odd? (1) m/2 is not an even integer (2) m-3 is an even integer

I chose D.

If m is an integer, is m odd?

(1) m/2 is not an even integer --> \frac{m}{2}\neq{even} could occur when m is odd as well as when m is even (10 and 5 for example) --> \frac{m}{2}=\frac{10}{2}=5\neq{even} and \frac{m}{2}=\frac{5}{2}=2.5\neq{even}. Not sufficient.

(2) m-3 is an even integer --> m-odd=even --> m=even+odd=odd. Sufficient.

Re: Number Property [#permalink]
21 Dec 2010, 07:37

Ok thanks guys. I assumed that 1) meant m/2 is an integer that is not even. I guess when they say it's not an even integer, I should always interpret it as anything but an even integer (therefore, it can be odd integer or odd non-integer)

Re: Number Property [#permalink]
21 Dec 2010, 07:41

Expert's post

psirus wrote:

Ok thanks guys. I assumed that 1) meant m/2 is an integer that is not even. I guess when they say it's not an even integer, I should always interpret it as anything but an even integer (therefore, it can be odd integer or odd non-integer)

Only integers can be even or odd, so "m/2 is not an even integer" means that m/2 is odd (integer) or not an integer at all.
_________________

Re: Number Property [#permalink]
21 Dec 2010, 08:29

I have just a quick question. How can you use 10 for an example in your explaination of m/2. m must always be a negative number. So actually 1 is not sufficient because you would never get a integer. Right?

Re: Number Property [#permalink]
21 Dec 2010, 08:39

1

This post received KUDOS

Expert's post

PASSINGGMAT wrote:

I have just a quick question. How can you use 10 for an example in your explaination of m/2. m must always be a negative number. So actually 1 is not sufficient because you would never get a integer. Right?

We are not told that m must be a negative number, so 10 is fine for an example.

Again: "m/2 is not an even integer" means that either m/2 is odd (integer) or not an integer at all.

\frac{m}{2}=\frac{10}{2}=5=odd --> m=even; \frac{m}{2}=\frac{5}{2}=2.5=not \ an \ integer --> m=odd.

Getting confused, probably a long day... [#permalink]
30 Nov 2011, 18:09

Can someone please help me understand this. Is my approach correct?

If m is an integer, is m odd?

1. m/2 is not an even number 2. m-3 is an even number

My understanding is that each choice should not lead to a "Maybe" answer. But can it be sufficient if it leads to a "NO" or does it always have to be a "YES".

1. If we take m=10, the result is 5 which is not even. Therefore statement is sufficient in answering No m is not odd.

2. 5-3=2 which is even. Therefore statement 2 is sufficient because it also has a unique Yes answer that m is odd.

Re: Getting confused, probably a long day... [#permalink]
02 Dec 2011, 07:08

Newbie here, but attempting to answer:

Statement 1: You tested an even number and got a result that was not an even number. You concluded that m is NOT odd, and that statement is sufficient. This could be true, but you should try out other numbers to ensure that m is NEVER odd.

What if m is 3? If m is 3, then m/2 gives 3/2, or 1.5. 1.5 is not an even number either. But m is now odd and the statement is still true.

This shows that m can be odd OR even. Insufficient.

Statement 2: Your approach is correct here. A simple rule for this statement is as follows:

odd +/- odd = even even +/- even = even odd +/- even = odd

This statement falls in the first category. We are subtracting an odd number and getting an even number. The only time this can happen is when the first number is also odd. So m is always odd. Sufficient.

Re: Getting confused, probably a long day... [#permalink]
05 Dec 2011, 10:32

pratk wrote:

Can someone please help me understand this. Is my approach correct?

If m is an integer, is m odd?

1. m/2 is not an even number 2. m-3 is an even number

My understanding is that each choice should not lead to a "Maybe" answer. But can it be sufficient if it leads to a "NO" or does it always have to be a "YES".

1. If we take m=10, the result is 5 which is not even. Therefore statement is sufficient in answering No m is not odd.

2. 5-3=2 which is even. Therefore statement 2 is sufficient because it also has a unique Yes answer that m is odd.

Thus the answer is D.

1. m = 10 so m/2=5 is not odd, you are right But You are missing one thing that m = 5, so m/2 = 2.5, which is not even but m is odd. Thus statement 1 is not sufficient. 2. Your reasoning is correct.

Re: Getting confused, probably a long day... [#permalink]
03 Feb 2012, 08:23

Expert's post

pratk wrote:

My understanding is that each choice should not lead to a "Maybe" answer. But can it be sufficient if it leads to a "NO" or does it always have to be a "YES".

1. If we take m=10, the result is 5 which is not even. Therefore statement is sufficient in answering No m is not odd.

2. 5-3=2 which is even. Therefore statement 2 is sufficient because it also has a unique Yes answer that m is odd.

Thus the answer is D.

Your understanding of DS is correct. It's a YES/NO DS question. In a Yes/No Data Sufficiency question, each statement is sufficient if the answer is “always yes” or “always no” while a statement is insufficient if the answer is "sometimes yes" and "sometimes no".

Though you're missing a point for statement (1), which says: m/2 is not an even integer. --> \frac{m}{2}\neq{even} could occur when m is odd as well as when m is even (10 and 5 for example) --> \frac{m}{2}=\frac{10}{2}=5\neq{even} and \frac{m}{2}=\frac{5}{2}=2.5\neq{even}. So this statement is not sufficient.

liftoff wrote:

Answer is C. But answer in statement A is No and Answer in statement 2 is Yes. funny one

First of all answer to the question is B, not C. Next, your case can never happen on the GMAT: as on the GMAT, two data sufficiency statements always provide TRUE information and these statements never contradict each other.

So we can not have answer NO from statement (1) and answer YES from statement (2) (as you got in your solution), because in this case statements would contradict each other.