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What is the sum of the first 17 terms of an arithmetic progression if the first term is -20 and last term is 28?

A. 68 B. 156 C. 142 D. 242 Answer: Option A
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Solution(By Apex Team)

First term of AP = a = -20 and last term = l = 28 Number of terms = n = 17 $\begin{aligned}&\text{ Sum of }\mathrm{AP}=\frac{\mathrm{n}}{2}(\mathrm{a}+\mathrm{l})\\ &=\frac{17}{2}(-20+28)\\ &=17\times4\\ &=68\end{aligned}$

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