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Question
Sum of the first 30 terms of an arithmetic progression is 0. If the first term is -29, then find the sum of the 28th, 29th and 30th terms of this arithmetic progression.
Options:
A. 81
B. 84
C. -84
D. -81

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Answer: Option A
: A

Let the common difference of the arithmetic progression be 'd'.
Sum of first 30 terms of the arithmetic progression
=302×[2(29)+(301)d]
Hence, 15(−58+29d) = 0
Hence, d=2
Sum of 28th, 29th and 30th term of this arithmetic progression
= 3(-29) + (27 + 28 +29) × 2 = 81

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