Find all School-related info fast with the new School-Specific MBA Forum

It is currently 19 Apr 2014, 22:18

Close

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
Your Progress

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

Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.

Events & Promotions

Events & Promotions in June
Open Detailed Calendar

If r and t are positive integers, is rt even?

  Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:
Manager
Manager
Joined: 30 Aug 2007
Posts: 62
Followers: 1

Kudos [?]: 0 [0], given: 0

If r and t are positive integers, is rt even? [#permalink] New post 02 Oct 2007, 12:30
00:00
A
B
C
D
E

Difficulty:

  5% (low)

Question Stats:

100% (00:00) correct 0% (00:00) wrong based on 1 sessions
Q28)
If r and t are positive integers, is rt even?

(1) r + t is odd.
(2) r^t is odd.
Director
Director
Joined: 17 Sep 2005
Posts: 932
Followers: 2

Kudos [?]: 17 [0], given: 0

GMAT Tests User
 [#permalink] New post 02 Oct 2007, 13:15
Each statement alone is SUFF.

I would chose D.

- Brajesh
Director
Director
Joined: 11 Sep 2006
Posts: 514
Followers: 1

Kudos [?]: 34 [0], given: 0

GMAT Tests User
 [#permalink] New post 03 Oct 2007, 08:37
A is sufficient. odd + odd = even. Odd + even = odd. Even + even = even. So if r+t is odd, one of the #'s is odd and one is even. Odd times an even is always even.

B is insufficient. 5^2 is 25, and is odd, and 5*2 is 10, which is even and satisfies the question. But 5^3 is also odd, and 5*3 is 15, which is odd. So you can't tell.

I go with A.
_________________

...there ain't no such thing as a free lunch...

Manager
Manager
User avatar
Joined: 18 Apr 2007
Posts: 123
Followers: 1

Kudos [?]: 4 [0], given: 0

GMAT Tests User
 [#permalink] New post 03 Oct 2007, 09:03
I agree with A.

[1] r+t = odd
The only way we can get an odd integer through addition is to add even+odd = odd. Therefore, we know one is even and one is odd, which is sufficient.

[2] r^t = odd
Knowing the rules of multiplication helps here. The only way to get an odd integer through multiplication is odd*odd = odd. So, the only thing this statement tells us is that r is odd. However, we don't know if t is even or odd. Therefore, this is insufficient.
Director
Director
Joined: 17 Sep 2005
Posts: 932
Followers: 2

Kudos [?]: 17 [0], given: 0

GMAT Tests User
 [#permalink] New post 03 Oct 2007, 09:09
uphillclimb wrote:
A is sufficient. odd + odd = even. Odd + even = odd. Even + even = even. So if r+t is odd, one of the #'s is odd and one is even. Odd times an even is always even.

B is insufficient. 5^2 is 25, and is odd, and 5*2 is 10, which is even and satisfies the question. But 5^3 is also odd, and 5*3 is 15, which is odd. So you can't tell.

I go with A.


I am out... :-) Good catch.....
Agree, it's A.

- Brajesh
Senior Manager
Senior Manager
Joined: 04 Jun 2007
Posts: 374
Followers: 1

Kudos [?]: 9 [0], given: 0

GMAT Tests User
Re: GMAT Prep 2: DS Q28 [#permalink] New post 03 Oct 2007, 10:14
avenger wrote:
Q28)
If r and t are positive integers, is rt even?

(1) r + t is odd.
(2) r^t is odd.


ST. 1
since r+t is odd,
if r=odd & t= even, then rt= even
SUFF

ST. 2
r^t is odd
so if r= odd and t=even then rt= even
but if r=odd and t=odd, then rt= odd
INSUFF

A.
CEO
CEO
User avatar
Joined: 29 Mar 2007
Posts: 2596
Followers: 16

Kudos [?]: 167 [0], given: 0

GMAT Tests User
Re: GMAT Prep 2: DS Q28 [#permalink] New post 03 Oct 2007, 23:56
avenger wrote:
Q28)
If r and t are positive integers, is rt even?

(1) r + t is odd.
(2) r^t is odd.


Quick and easy A. These are my favorite Quant questions b/c if u know the rules of odds and evens, these probs are a breaze.

rt even?

so either E*E or O*E will give us an even.

S1: r+t = odd. Only E+O yields an odd (when positive integers, r and t are non 0 values and are integers). So this is suff.

S2:
r^t is odd. r^t can be 5^6 or 5^5. Both are still odd, but when multiplied, yield different results.

Insuff.
Manager
Manager
Joined: 30 Aug 2007
Posts: 62
Followers: 1

Kudos [?]: 0 [0], given: 0

 [#permalink] New post 04 Oct 2007, 15:18
OA is A. I was caught out as well like Brajesh.

Thanks for the explanations.

A.
  [#permalink] 04 Oct 2007, 15:18
    Similar topics Author Replies Last post
Similar
Topics:
New posts If r, s, and t are positive integers, is r + s + t even? (1) gluon 5 15 Sep 2007, 14:46
New posts Is the positive integer r an even number? (1) r is a prime dancinggeometry 2 05 Sep 2008, 02:44
New posts Experts publish their posts in the topic If r and t are positive integers, is rt even? msand 5 31 Jan 2010, 13:28
New posts Experts publish their posts in the topic if | r | != 1 is integer r even 1 r is not positive 2 2r rxs0005 9 14 Aug 2010, 03:38
New posts 1 Is Integer r even? enigma123 7 06 Jul 2011, 06:51
Display posts from previous: Sort by

If r and t are positive integers, is rt even?

  Question banks Downloads My Bookmarks Reviews Important topics  


GMAT Club MBA Forum Home| About| Privacy Policy| Terms and Conditions| GMAT Club Rules| Contact| Sitemap

Powered by phpBB © phpBB Group and phpBB SEO

Kindly note that the GMAT® test is a registered trademark of the Graduate Management Admission Council®, and this site has neither been reviewed nor endorsed by GMAC®.