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a1 = 7 a2 = 8 a3 = 10 [#permalink]
 11 Sep 2011, 04:57
Question Stats:
66% (00:00) correct
33% (03:46) wrong based on 0 sessions
Please find the attached question.. I have a curious question... quite honesly i did not understand what an= a_(n-3) +7 meant... i assumed something got cut off maybe it was a1*(n-3) + 7 i am used to seeing a(n) = a(n-3) +7 or watching the "n-3" similar to the "n" (as a footer) in the question in my quant thus far so my questions are... 1. so do we get to see such a thing on the real test? i mean should i get used to this convention? and most importantly are there others? 2. if not, i would appreciate if the Veritas instructors have a look at this and help make the question more clearer Thanks!
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veritas test q a1 = 7.jpg [ 94.44 KiB | Viewed 1102 times ]
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Re: a1 = 7 a2 = 8 a3 = 10 [#permalink]
11 Sep 2011, 08:50
1
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I am sure that's just a typo. it means a(n) = a(n-3)+7.
Given a1 = 7 , a2 =8, a3 =10
1. Sufficient
n is multiple of 3.
a3 = 10
a6 = a3+7
a9 = a6+7 = a3+2*7
a12 = a3+3*7
so basically remainder of a(n) when n is divided by 7 and when n is multiple of 3 = remainder of a3 when its
divided by 7
= remainder of (10/7) = 3
2. Not sufficient
a2 = 8, remainder of a2/7 = 1
a4 =a1+7 = 14;=>remainder of 14/7= 0
Answer is A.
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Re: a1 = 7 a2 = 8 a3 = 10 [#permalink]
12 Sep 2011, 03:47
Write few elements of series a1=7 a2=8 a3=10 a4=a1+7=14 a5=a2+7=15 a6=a3+7=17 a7=a4+7=21 a8=a5+7=22 a9=a6+7=24 Stmt1: n is a multiple of 3. a3,a6,a9 all leaving remainder of 3. Sufficient. Stmt2: n is an even number a2=8 leaves remainder 1 a4=14 leaves remainder 0. Not sufficient. OA A.
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Re: a1 = 7 a2 = 8 a3 = 10 [#permalink]
12 Sep 2011, 04:15
Yes.. I was dumbstruck for a moment when I saw this question in the test. But it can only be a(n-3).. So I went ahead and solved it that way..
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Re: a1 = 7 a2 = 8 a3 = 10 [#permalink]
13 Sep 2011, 22:16
viks4gmat wrote: Please find the attached question.. I have a curious question... quite honesly i did not understand what an= a_(n-3) +7 meant... i assumed something got cut off maybe it was a1*(n-3) + 7 i am used to seeing a(n) = a(n-3) +7 or watching the "n-3" similar to the "n" (as a footer) in the question in my quant thus far so my questions are... 1. so do we get to see such a thing on the real test? i mean should i get used to this convention? and most importantly are there others? 2. if not, i would appreciate if the Veritas instructors have a look at this and help make the question more clearer Thanks! Yes, it is a typo. Subscripts and superscripts behave differently in different software and hence such errors creep up sometimes. You should not see such a thing in actual GMAT but if you do, think what it should be. Since you have subscripts on A everywhere, this logically seems like a subscript. Anyway, we know that '_' is not a mathematical symbol and in series questions, more often than not, subsequent terms are related to previous terms through some relation.
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Re: a1 = 7 a2 = 8 a3 = 10 [#permalink]
17 Sep 2011, 03:29
Thanks Karishma.. yup.. i agree that some errors can creep in no matter what.... Murphy's law!! was just curious if this denotes something i dont know... on recognizing this as a subscript.... well i went a step ahead to assume its a1 whose head was cut off from the base  so i think too much thinking cost me this question
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Re: a1 = 7 a2 = 8 a3 = 10
[#permalink]
17 Sep 2011, 03:29
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