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A series contains the terms – 1, -4, -7, -10, …
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06 Feb 2022, 09:29
06 Feb 2022, 09:29
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Question Stats:
70% (01:34) correct
30% (01:17) wrong based on 10 sessions
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A series contains the terms – 1, -4, -7, -10, ……….
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 |
\(\)sum of first 50 terms of given series |
\(\)- 5000 |
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
A series contains the terms – 1, -4, -7, -10, …
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06 Feb 2022, 11:35
06 Feb 2022, 11:35
2
Expert Reply
In this question, we can make use of the Sum of Arithmetic series formula to calculate the sum of first 50 terms.
The sum formula is given by
\(S_n=\frac{n}{2}(2a_1+(n-1)d)\)
where \(n\) is the number of terms, \(a_1\) is the first term in the series and \(d\) is the difference between two consecutive terms given by
\(d=-4-(-1)=-3\)
\(S_{50}=\frac{50}{2}(2(-1)+(50-1)(-3))\)
\(S_{50}=25(-2-147)\)
\(S_{50}=-3725\)
Hence, the answer is A.
The sum formula is given by
\(S_n=\frac{n}{2}(2a_1+(n-1)d)\)
where \(n\) is the number of terms, \(a_1\) is the first term in the series and \(d\) is the difference between two consecutive terms given by
\(d=-4-(-1)=-3\)
\(S_{50}=\frac{50}{2}(2(-1)+(50-1)(-3))\)
\(S_{50}=25(-2-147)\)
\(S_{50}=-3725\)
Hence, the answer is A.
gmatclubot
A series contains the terms – 1, -4, -7, -10, … [#permalink]
06 Feb 2022, 11:35
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