Author 
Message 
Intern
Joined: 09 Jan 2009
Posts: 10

If a, b, and c are integers, is the number divisible by 3? [#permalink]
Show Tags
18 Jan 2009, 19:47
Question Stats:
0% (00:00) correct 0% (00:00) wrong based on 1 sessions
HideShow timer Statistics
If a, b, and c are integers, is the number divisible by 3? (1) a + b is divisible by 3. (2) c is divisible by 3. == Message from GMAT Club Team == This is not a quality discussion. It has been retired. If you would like to discuss this question please repost it in the respective forum. Thank you! To review the GMAT Club's Forums Posting Guidelines, please follow these links: Quantitative  Verbal Please note  we may remove posts that do not follow our posting guidelines. Thank you.



Senior Manager
Joined: 30 Nov 2008
Posts: 482
Schools: Fuqua

Re: 1000 DS [#permalink]
Show Tags
18 Jan 2009, 20:47
Some thing is missing in the question part. Which number is the one to find whether it is divisible by 3 or not?



Intern
Joined: 09 Jan 2009
Posts: 10

Re: 1000 DS [#permalink]
Show Tags
19 Jan 2009, 07:50
Sorry...Here is the Question again.....
If a, b, and c are integers, is the number 3(a+b)c divisible by 3?
(1) a + b is divisible by 3. (2) c is divisible by 3.



Director
Joined: 29 Aug 2005
Posts: 836

Re: 1000 DS [#permalink]
Show Tags
19 Jan 2009, 08:01
vicky81 wrote: Sorry...Here is the Question again.....
If a, b, and c are integers, is the number 3(a+b)c divisible by 3?
(1) a + b is divisible by 3. (2) c is divisible by 3. Should be B. If c=3x, 3(a+b)c= 3(a+b)3x=3(a+bx)



Intern
Joined: 09 Jan 2009
Posts: 10

Re: 1000 DS [#permalink]
Show Tags
19 Jan 2009, 08:08
Lets assume....
a=1,b=0 and c=3 ( as a,b and C are integers)
so 3(a+b)c = 3(1+0) 3 = 0 ...0 is not divisible by 3.
I think the answer should be C ....
What do u say ??



Director
Joined: 29 Aug 2005
Posts: 836

Re: 1000 DS [#permalink]
Show Tags
19 Jan 2009, 09:02
vicky81 wrote: Lets assume....
a=1,b=0 and c=3 ( as a,b and C are integers)
so 3(a+b)c = 3(1+0) 3 = 0 ...0 is not divisible by 3.
I think the answer should be C ....
What do u say ?? vicky, I believe zero is evenly divisible by 3  every number is, except zero itself.



Senior Manager
Joined: 30 Nov 2008
Posts: 482
Schools: Fuqua

Re: 1000 DS [#permalink]
Show Tags
19 Jan 2009, 09:13
IMO B.
Here is a simple rule worth remembering. For any 2 integers, a and b,
case 1, if a is a multiple of n, b is a multiple of n, then a + b or a  b will be a multiple of n. case 1, if a is a multiple of n, b is NOT a multiple of n, then a + b or a  b will NOT be a multiple of n. case 1, if a is NOT a multiple of n, b is NOT a multiple of n, then a + b or a  b CAN be a multiple of n.
The question stem is  Is 3(a+b)c divisible by 3? Here first term is 3(a+b) and second term is c. First term is clearly multple of 3. So to answer the question, we need to know whether c is divisble by 3. And based on the above rules we can say whether the number in question is divisible by 3.
Stmt 1  a + b is divisible by 3. This is immaterial since we know that first term is already divisible by 3. Nothing is mentioned abt c. Hence In sufficient.
Stmt 2  c is divisible by 3. This clue is sufficient now that both the first and the second terms are divisible by 3. Hence the number is question is divisible by 3. Sufficient.



Intern
Joined: 16 Jan 2009
Posts: 14

Re: 1000 DS [#permalink]
Show Tags
19 Jan 2009, 09:49
If a, b, and c are integers, is the number 3(a+b)c divisible by 3? (1) a + b is divisible by 3. (2) c is divisible by 3. This is a yes/no question. since 3(a+b) is a multiple of 3 ..it is divisible by 3 so if c is divisible then the answer would be yes if c is not divisible by 3 then the answer would be no. stmt 1: is not sufficient as theres no information about c..so the answer could be Yes or No. stmt 2: is sufficient as it says c is divisible by 3 so the answer is a YES. answer is B. www.graduatetutor.com



Manager
Joined: 04 Jan 2009
Posts: 235

Re: 1000 DS [#permalink]
Show Tags
19 Jan 2009, 09:58
vicky81 wrote: Sorry...Here is the Question again.....
If a, b, and c are integers, is the number 3(a+b)c divisible by 3?
(1) a + b is divisible by 3. (2) c is divisible by 3. 1 is not providing additional info. 2 is sufficient. Hence, B.
_________________
 tusharvk



Manager
Joined: 02 Sep 2008
Posts: 103

Re: 1000 DS [#permalink]
Show Tags
20 Jan 2009, 16:44
If a, b, and c are integers, is the number 3(a+b)c divisible by 3?
(1) a + b is divisible by 3. (2) c is divisible by 3.
Lets check the equation in question.
there are two parts of the equation. 3(a+b) and then c.
now 3(a+b) will always be divisible by 3. as it represents some thing like 3x. now for this equation to be divisible by 3 we only need to know whether c is divisible by 3 or not. this information is amply supplied by statement 2.
Hence the answer is B.



Manager
Joined: 13 Jan 2009
Posts: 168
Schools: Harvard Business School, Stanford

Re: 1000 DS [#permalink]
Show Tags
21 Jan 2009, 03:40
milind1979 wrote: If a, b, and c are integers, is the number 3(a+b)c divisible by 3?
(1) a + b is divisible by 3. (2) c is divisible by 3.
Lets check the equation in question.
there are two parts of the equation. 3(a+b) and then c.
now 3(a+b) will always be divisible by 3. as it represents some thing like 3x. now for this equation to be divisible by 3 we only need to know whether c is divisible by 3 or not. this information is amply supplied by statement 2.
Hence the answer is B. The answer is B, definitely. == Message from GMAT Club Team == This is not a quality discussion. It has been retired. If you would like to discuss this question please repost it in the respective forum. Thank you! To review the GMAT Club's Forums Posting Guidelines, please follow these links: Quantitative  Verbal Please note  we may remove posts that do not follow our posting guidelines. Thank you.










