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Question: Answered & Verified by Expert
A student read common difference of an A. P. as

-2 instead of 2 and got the sum of first 5 terms as -5 . Actual sum of first five terms is
MathematicsSequences and SeriesBITSATBITSAT 2020
Options:
  • A 25
  • B -25
  • C -35
  • D 35
Solution:
2711 Upvotes Verified Answer
The correct answer is: 35
$\frac{5}{2}\{2 \mathrm{a}+4(-2)\}=-5 \Rightarrow 2 \mathrm{a}=6$

$\therefore$ Actual sum $=\frac{5}{2}\{6+4(2)\}=35$

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