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
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Second to last term
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beat_gmat_09
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Rahul@gurome
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Let the sequence is r, 3r, 9r, 27r....
(1) It's given that r = 3. So 4th term = 27 * 3 = 81
So, (1) is SUFFICIENT.
(2) The second-to-last term does not give is the information about the first term and hence the 4th term.
So, (2) is NOT SUFFICIENT.
The correct answer is [spoiler](A)[/spoiler].
(1) It's given that r = 3. So 4th term = 27 * 3 = 81
So, (1) is SUFFICIENT.
(2) The second-to-last term does not give is the information about the first term and hence the 4th term.
So, (2) is NOT SUFFICIENT.
The correct answer is [spoiler](A)[/spoiler].
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beat_gmat_09
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Cant we know the first term by knowing the ques stmt and (2) -> 3^10, as 3.Rahul@gurome wrote:Let the sequence is r, 3r, 9r, 27r....
(1) It's given that r = 3. So 4th term = 27 * 3 = 81
So, (1) is SUFFICIENT.
(2) The second-to-last term does not give is the information about the first term and hence the 4th term.
So, (2) is NOT SUFFICIENT.
The correct answer is [spoiler](A)[/spoiler].
the sequence becomes 3, 3^2, 3^3 .... 3^10
in what other cases could second-to last term come out as 3^10 knowing tht each term is 3 times the previous ?
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Rahul@gurome
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The main question says that "each term is three times the previous term", and (2) says that second-to last term is 3^10, but combining this information we cannot say that the sequence is definitely starting from "3", it can also start from 3^2 or 3^3, and so it's 4th term will keep on changing.beat_gmat_09 wrote: Cant we know the first term by knowing the ques stmt and (2) -> 3^10, as 3.
the sequence becomes 3, 3^2, 3^3 .... 3^10
in what other cases could second-to last term come out as 3^10 knowing tht each term is 3 times the previous ?
Does that answer your query?
Rahul Lakhani
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+91-99201 32411 (India)
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beat_gmat_09
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Got it.Rahul@gurome wrote:The main question says that "each term is three times the previous term", and (2) says that second-to last term is 3^10, but combining this information we cannot say that the sequence is definitely starting from "3", it can also start from 3^2 or 3^3, and so it's 4th term will keep on changing.beat_gmat_09 wrote: Cant we know the first term by knowing the ques stmt and (2) -> 3^10, as 3.
the sequence becomes 3, 3^2, 3^3 .... 3^10
in what other cases could second-to last term come out as 3^10 knowing tht each term is 3 times the previous ?
Does that answer your query?
