It is currently 27 Jun 2017, 12:26

### GMAT Club Daily Prep

#### Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.

Customized
for You

we will pick new questions that match your level based on your Timer History

Track

every week, we’ll send you an estimated GMAT score based on your performance

Practice
Pays

we will pick new questions that match your level based on your Timer History

# Events & Promotions

###### Events & Promotions in June
Open Detailed Calendar

# a/b even, a-b even,which is odd ? 1. a/2 2. b/2 3.

Author Message
CEO
Joined: 15 Aug 2003
Posts: 3454
a/b even, a-b even,which is odd ? 1. a/2 2. b/2 3. [#permalink]

### Show Tags

12 Sep 2003, 04:09
00:00

Difficulty:

(N/A)

Question Stats:

0% (00:00) correct 0% (00:00) wrong based on 0 sessions

### HideShow timer Statistics

This topic is locked. If you want to discuss this question please re-post it in the respective forum.

a/b even, a-b even,which is odd ?

1. a/2
2. b/2
3. a+b/2
4. a
5. b
Senior Manager
Joined: 22 Aug 2003
Posts: 257
Location: Bangalore

### Show Tags

12 Sep 2003, 07:44
i am getting both a & b as even given that : a/b=even & a-b=even
In that case none of the answers are coming to be odd.
- Vicks
Senior Manager
Joined: 22 May 2003
Posts: 329
Location: Uruguay

### Show Tags

12 Sep 2003, 17:27
Same as Vicky.. I get a,b both EVEN

Thanks

Martin
CEO
Joined: 15 Aug 2003
Posts: 3454

### Show Tags

12 Sep 2003, 17:58
mystery wrote:

i have no idea how you guys are getting 3.

SVP
Joined: 30 Oct 2003
Posts: 1790
Location: NewJersey USA

### Show Tags

19 Jan 2004, 09:10
I think none of them match.
if a = 8 b = 4
8/4 is even 8-4 is even

1. a/2 = 8/2 = even
2. b/2 = 4/2 = even
3. a+b/2 = 8+4/2 = even
4. a is even
5. b is even
Intern
Joined: 05 Jan 2004
Posts: 27
Location: Los Angeles

### Show Tags

19 Jan 2004, 10:01
According to me none of the answers could match

if a/b = even then we can say a = (2n)b where n is any integer

a-b = even, then we can say that a-b = 2k where k is any integer

then we can say that b = 2k/(2n-1)

and b could be odd or even, if k = 3, n = 2 b = even
and b could be a fraction as well, not even an integer for other values

so there is really no way to say

That is what I think
Director
Joined: 28 Oct 2003
Posts: 501
Location: 55405

### Show Tags

19 Jan 2004, 10:34
As everyone has shown, none of them MUST be odd, however, if you set:

A=0
B=6

Then A/B=0 (even) and A-B=-6 (even).

a/2 even
b/2 odd
a+b/2 odd
a even
b even.
SVP
Joined: 30 Oct 2003
Posts: 1790
Location: NewJersey USA

### Show Tags

19 Jan 2004, 11:15
Stoolfi's obsession with zero plays out.

I will watchout for zero in every problem now onwards.
Intern
Joined: 05 Dec 2003
Posts: 47
Location: LA

### Show Tags

19 Jan 2004, 18:14
a/b even, a-b even,which is odd ?

1. a/2
2. b/2
3. a+b/2
4. a
5. b

I pick 3!

A and B must be even. (Cause if A is odd and B is even, you will not get an integer.) So, go through the answer choices.

1) Even/2 is even 4/2= 2
2) Even/2 is even again

Which leaves us to C. Remember, when playing odd and even, choosing numbers doesn't always work. If you pick A=10, B=14; then (10+14)/2= 12. And then you're confused.

Look on the number line... 10 . 11 . 12 . 13. 14, the middle number if 12.

But if you choose A=2, B=4.
Look on the number line.. 2 . 3 . 4.. the middle number if 3;
so (2+4)/2 = 3 which is odd.

Remember how to choose numbers in PS and DS will definately help you. Don't choose random numbers, know what you are trying to prove.
Senior Manager
Joined: 11 Nov 2003
Posts: 356
Location: Illinois

### Show Tags

19 Jan 2004, 21:24
I think this problem should be addressed in more structured way:

a/b = even => a = even (it does not matter whether b is odd or even, a will always be even)

a-b = even => There are only two possibilities:
a= odd & b = odd OR a= even & b = even

Considering both statements, we can conclude that a and b both should be even.

Now pick numbers, but while picking the numbers, also check that it satisfy the original statements given in the question. For example, we can not select a = 10 and b = 14. Because although both of them are even, they do not satisfy the first statment a/b = even.

a = 2, 4, 6, ,8, 10, 12.......
b = 2, 4, 6, 8, 10, 12.......

Now find few possible pairs of a and b. (2,2) is not possible (does not satisfy the given equation)

possible pairs could be (4,2), (8, 2), (8,4), (12,2), (12,6)

Now check each answer choice. Only choice 3 can become ODD and that too NOT ALWAYS. Because if a = 8, b = 4, then a+b/2 = 6(even).

So I think the question should probably be worded as "which of the following COULD BE ODD". If it is "which of the following MUST BE ODD" then I guess none of the choices meet the criteria.

Director
Joined: 28 Oct 2003
Posts: 501
Location: 55405

### Show Tags

19 Jan 2004, 22:27
Hey-- gmatblast and gmatanh--

Did I make a mistake or did you skip my post?

Using these values:

A=0
B=6

Both b/2 and a+b/2 can be made odd.
Intern
Joined: 05 Dec 2003
Posts: 47
Location: LA

### Show Tags

19 Jan 2004, 22:55
Yikes.. you are right.. what's the correct answer?
Senior Manager
Joined: 11 Nov 2003
Posts: 356
Location: Illinois

### Show Tags

20 Jan 2004, 08:08
stoolfi wrote:
Hey-- gmatblast and gmatanh--

Did I make a mistake or did you skip my post?

Using these values:

A=0
B=6

Both b/2 and a+b/2 can be made odd.

Stoofi,

I did not skip your post. I was just trying to address the problem in more procedural way. I understand whet you tried to say in your post. And I think I missed the point you were trying to make (in hurry..). This resulted in long and unnecessary method.

I think that the question is missing additional information.
Intern
Joined: 19 Nov 2003
Posts: 5
Location: Arizona

### Show Tags

24 Jan 2004, 04:39
[quote="praetorian123"]a/b even, a-b even,which is odd ?

1. a/2
2. b/2
3. a+b/2
4. a
5. b[/quote]

I got Answer 3. i assumed a=4 b=2 4/2= 2 (even). 4-2=2 (even-even=even)
Re: PS : even/odd   [#permalink] 24 Jan 2004, 04:39
Display posts from previous: Sort by