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If n is a positive integer and r is the remainder when 4+7n [#permalink]
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13 Oct 2008, 19:57
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If n is a positive integer and r is the remainder when 4+7n is divided by 3, what is the value of r? 1) n+1 is divisible by 3 2) n > 20 == 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.



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Re: DS Problem [#permalink]
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13 Oct 2008, 21:09
udribat wrote: If n is a positive integer and r is the remainder when 4+7n is divided by 3, what is the value of r?
1) n+1 is divisible by 3
2) n > 20 A. 1: n+1 = 3k, where k is an integer. so if n is divided by 3, the reminder is 2. then when 7n is divided by 3, reminder is 2. so 2+4 is 6. then r = 0. 2: n > 20 tells nothing. nsf.
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Re: DS Problem [#permalink]
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13 Oct 2008, 21:19
GMAT TIGER wrote: udribat wrote: If n is a positive integer and r is the remainder when 4+7n is divided by 3, what is the value of r?
1) n+1 is divisible by 3
2) n > 20 A. 1: n+1 = 3k, where k is an integer. so if n is divided by 3, the reminder is 2. then when 7n is divided by 3, reminder is 2. so 2+4 is 6. then r 0. 2: n > 20 tells nothing. nsf. everything is correct, just wanted to add that (4+7n)/3=4/3+7n/3=4/3+2



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Re: DS Problem [#permalink]
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13 Oct 2008, 22:03
udribat wrote: If n is a positive integer and r is the remainder when 4+7n is divided by 3, what is the value of r?
1) n+1 is divisible by 3
2) n > 20 alternatively: 1: n + 1 = 3k where k is an integer. 4 + 7n = 1+1+1+1+n+n+n+n+3n = 4(1+n) + 3n in the above expression, 4(1+n) is divisible by 3, r is 0 for this one. 3n is less than 3(n+1) or (3n + 3) by 3. if n+1 is divisible by 3, then (3n+3) is also divisibly by 3. also divisibly by 3 is any addition or substraction of any value that is multiple of 3. so (3n + 3)  3 = 3n, whcih is also divisibly by 3. so r = 0. 2: n > 20 doesnot tell much about its divisibility by 3.
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Re: DS Problem [#permalink]
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13 Oct 2008, 22:06
kazakhb wrote: GMAT TIGER wrote: udribat wrote: If n is a positive integer and r is the remainder when 4+7n is divided by 3, what is the value of r?
1) n+1 is divisible by 3
2) n > 20 A. 1: n+1 = 3k, where k is an integer. so if n is divided by 3, the reminder is 2. then when 7n is divided by 3, reminder is 2. so 2+4 is 6. then r 0. 2: n > 20 tells nothing. nsf. everything is correct, just wanted to add that (4+7n)/3 = 4/3 + 7n/3 = 4/3 + 2check again the highlighted part, whcih is not correct and should be (4/3 + 2/3), above.
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Re: DS Problem [#permalink]
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13 Oct 2008, 22:45
udribat wrote: If n is a positive integer and r is the remainder when 4+7n is divided by 3, what is the value of r?
1) n+1 is divisible by 3
2) n > 20 From stmt1: n + 1 = 3x for x = 0, 1,2,3,.... OR, n = 3x  1 Thus, 7n + 4 = (21x  3) and this is divisible by 3 for any value of x. Hence, sufficient. Stmt2 is not sufficient.



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Re: DS Problem [#permalink]
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14 Oct 2008, 01:45
Quote: check again the highlighted part, whcih is not correct and should be (4/3 + 2/3), above.
ohhh, right, man; my mistake



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Re: DS Problem [#permalink]
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14 Oct 2008, 07:21
kazakhb wrote: Quote: check again the highlighted part, whcih is not correct and should be (4/3 + 2/3), above.
ohhh, right, man; my mistake check again the highlighted part, (which is not correct).
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Re: DS Problem [#permalink]
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14 Oct 2008, 21:08
GMAT TIGER wrote: kazakhb wrote: Quote: check again the highlighted part, whcih is not correct and should be (4/3 + 2/3), above.
ohhh, right, man; my mistake check again the highlighted part, (which is not correct). really? == 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.










