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In a sequence of terms in which each term is three times the [#permalink]
 15 Feb 2011, 08:28
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In a sequence of terms in which each term is three times the previous term, what is the fourth term? (1) The first term is 3. (2) The second-to-last term is 3^10. I think the ans should be D. But OA is different.
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Re: Sequence of terms MGMAT [#permalink]
15 Feb 2011, 08:35
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mariyea wrote: In a sequence of terms in which each term is three times the previous term, what is the fourth term?
(1) The first term is 3.
(2) The second-to-last term is 3^10.
I think the ans should be D. But OA is different. In a sequence of terms in which each term is three times the previous term, what is the fourth term?(1) The first term is 3 --> sequence is: 3, 9, 27, 81, ... so the fourth term is 81. Sufficient. (2) The second-to-last term is 3^10 --> since we don't know how many terms are there in the sequence then we don't know which term is second-to-last. For example: if it's third term then fourth (and last) will be 3^11, if it's fifth term then the fourth term is 3^9, ... Not sufficient. Answer: A.
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Re: Sequence of terms MGMAT [#permalink]
15 Feb 2011, 08:59
Bunuel wrote: mariyea wrote: In a sequence of terms in which each term is three times the previous term, what is the fourth term?
(1) The first term is 3.
(2) The second-to-last term is 3^10.
I think the ans should be D. But OA is different. In a sequence of terms in which each term is three times the previous term, what is the fourth term?(1) The first term is 3 --> sequence is: 3, 9, 27, 81, ... so the fourth term is 81. Sufficient. (2) The second-to-last term is 3^10 --> since we don't know how many terms are there in the sequence then we don't know which term is second-to-last. For example: if it's third term then fourth (and last) will be 3^11, if it's fifth term then the fourth term is 3^9, ... Not sufficient. Answer: A. I had to think about that for a bit before I could sincerely agree with you, Bunuel. Thanks!
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Re: Sequence of terms MGMAT [#permalink]
15 Feb 2011, 11:03
Bunuel wrote: mariyea wrote: In a sequence of terms in which each term is three times the previous term, what is the fourth term?
(1) The first term is 3.
(2) The second-to-last term is 3^10.
I think the ans should be D. But OA is different. In a sequence of terms in which each term is three times the previous term, what is the fourth term?(1) The first term is 3 --> sequence is: 3, 9, 27, 81, ... so the fourth term is 81. Sufficient. (2) The second-to-last term is 3^10 --> since we don't know how many terms are there in the sequence then we don't know which term is second-to-last. For example: if it's third term then fourth (and last) will be 3^11, if it's fifth term then the fourth term is 3^9, ... Not sufficient. Answer: A. You are truly awesome .. with DS.... i kinda assumed it to be 2nd term when said 2nd to last assuming that there r only 4 terms...thanks bunuel...
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Re: Sequence of terms MGMAT [#permalink]
05 Mar 2011, 21:57
Ans : a , in second statment we dont know where serise start it can start from any no so insuff.
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Re: Sequence of terms MGMAT [#permalink]
06 Mar 2011, 13:18
Good question.
First one is sufficient, as we have the rate at which each term is changing and first term which are enough to calculate what is neeed.
Second one is not sufficient , because we dont know the starting term and no of terms.
Hence A is the answer.
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Re: In a sequence of terms in which each term is three times the [#permalink]
13 Jan 2012, 16:39
Bunuel wrote: mariyea wrote: In a sequence of terms in which each term is three times the previous term, what is the fourth term?
(1) The first term is 3.
(2) The second-to-last term is 3^10.
I think the ans should be D. But OA is different. regarding the second statement. Someone could interpret the second-to-last term as the ratio between the second and the last term. Since we know that it is an exponential expression dividing the second with the last term should result a fraction smaller than 1. Therefore, someone could assume that the second statement is wrong. is my reasoning valid?
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Re: In a sequence of terms in which each term is three times the [#permalink]
16 Jan 2012, 17:24
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SonyGmat wrote: Bunuel wrote: mariyea wrote: In a sequence of terms in which each term is three times the previous term, what is the fourth term?
(1) The first term is 3.
(2) The second-to-last term is 3^10.
I think the ans should be D. But OA is different. regarding the second statement. Someone could interpret the second-to-last term as the ratio between the second and the last term. Since we know that it is an exponential expression dividing the second with the last term should result a fraction smaller than 1. Therefore, someone could assume that the second statement is wrong. is my reasoning valid? Responding to a pm. If it were the case it would have been something like "the ratio of second to last term is ..." Also on the GMAT, two data sufficiency statements always provide TRUE information and these statements never contradict each other. So if on the GMAT your interpretation of the statements leads you to conclude that the statements are impossible/incorrect or contradict each other then the case would be that your interpretation is wrong not the statements.
_________________
PLEASE READ AND FOLLOW: 11 Rules for Posting!!!
RESOURCES: [GMAT MATH BOOK]; 1. Triangles; 2. Polygons; 3. Coordinate Geometry; 4. Factorials; 5. Circles; 6. Number Theory; 7. Remainders; 8. Overlapping Sets; 9. PDF of Math Book; 10. Remainders
COLLECTION OF QUESTIONS:
PS: 1. Tough and Tricky questions; 2. Hard questions; 3. Hard questions part 2; 4. Standard deviation; 5. Tough Problem Solving Questions With Solutions; 6. Probability and Combinations Questions With Solutions; 7 Tough and tricky exponents and roots questions; 8 12 Easy Pieces (or not?); 9 Bakers' Dozen; 10 Algebra set. NEW!!! ,11 Mixed Questions NEW!!!, 12 Fresh Meat NEW!!!
DS: 1. DS tough questions; 2. DS tough questions part 2; 3. DS tough questions part 3; 4. DS Standard deviation; 5. Inequalities; 6. 700+ GMAT Data Sufficiency Questions With Explanations; 7 Tough and tricky exponents and roots questions; 8 The Discreet Charm of the DS ; 9 Devil's Dozen!!!; 10 Number Properties set. NEW!!!, 11 New DS set. NEW!!!
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Re: In a sequence of terms in which each term is three times the [#permalink]
09 Jul 2012, 02:54
thanks brunel for pointing out.. you are a jem
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In a sequence of terms in which each term is three times the [#permalink]
29 Nov 2012, 03:04
In a sequence of terms in which each term is three times the previous term, what is the fourth term?
(1) The first term is 3.
(2) The second-to-last term is 310.
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Re: In a sequence of terms in which each term is three times the [#permalink]
29 Nov 2012, 03:07
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Re: In a sequence of terms in which each term is three times the
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29 Nov 2012, 03:07
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