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Retired Moderator
Joined: 10 Apr 2015
Posts: 6218
Given Kudos: 136
In sequence X, term_1 = 3, term_2 =7, term_3 = 15,
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10 Aug 2022, 06:23
10 Aug 2022, 06:23
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25% (00:42) correct
74% (00:39) wrong based on 31 sessions
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In sequence X, \(t_1 = 3\), \(t_2 =7\), \(t_3 = 15\), and \(t_4 = 31\)
A) Quantity A is greater.
B) Quantity B is greater.
C) The two quantities are equal.
D) The relationship cannot be determined from the information given.
Quantity A |
Quantity B |
\(t_5\) of sequence X |
\(63\) |
A) Quantity A is greater.
B) Quantity B is greater.
C) The two quantities are equal.
D) The relationship cannot be determined from the information given.
Retired Moderator
Joined: 10 Apr 2015
Posts: 6218
Given Kudos: 136
Re: In sequence X, term_1 = 3, term_2 =7, term_3 = 15,
[#permalink]
13 Aug 2022, 07:30
13 Aug 2022, 07:30
3
GreenlightTestPrep wrote:
In sequence X, \(t_1 = 3\), \(t_2 =7\), \(t_3 = 15\), and \(t_4 = 31\)
A) Quantity A is greater.
B) Quantity B is greater.
C) The two quantities are equal.
D) The relationship cannot be determined from the information given.
Quantity A |
Quantity B |
\(t_5\) of sequence X |
\(63\) |
A) Quantity A is greater.
B) Quantity B is greater.
C) The two quantities are equal.
D) The relationship cannot be determined from the information given.
I created this question to highlight the fact that the GRE does not test our ability to find missing terms in a sequence unless the sequence is defined for us.
The reason is that there's no way that we can definitively determine ONE (and ONLY ONE) pattern in a given sequence.
Consider this example: 1, 2, 4, __
What's the missing term here?
Well, if we read the sequence as doubling from one term to the next, the next term is 8
HOWEVER, if we notice that we keep adding successively larger integers to each term (i.e., add 1, then add 2, then add 3, etc.) the next term is 7
Likewise, (if we want to get a bit silly), we might look at the given sequence (5, 10, 15, 20, 25, __) and say that the next term is 88. Why?
Because 5 is my favorite number, 10 is my 2nd favorite number, 15 is my 3rd favorite number, ... and 88 is 6th favorite number.
So, although you might have found a certain pattern in the sequence (double and add 1), we can't be certain that this is THE pattern.
This means t_5 can have ANY numeric value.
Answer: D
Re: In sequence X, term_1 = 3, term_2 =7, term_3 = 15,
[#permalink]
29 Sep 2025, 02:49
29 Sep 2025, 02:49
1
following are the cardinal rules for establishing a sequence
1) first term or last term should be given
2) common difference must be given
3) number of terms must be given (optional cuz an infinite sequence is also a sequence)
the question follows only rule 1 so its D
1) first term or last term should be given
2) common difference must be given
3) number of terms must be given (optional cuz an infinite sequence is also a sequence)
the question follows only rule 1 so its D
