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Mathematics · JEE | SEQUENCES AND SERIES
हिन्दीThe sum of some terms of a G.P. is \( 315 \) whose first term and the common ratio are \( 5 \) and \( 2 \), respectively. Find the number of terms.
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Correct answer · Option C
5
Explanation
Given \( a = 5, r = 2, S_n = 315 \). Using \( S_n = \frac{a(r^n-1)}{r-1} \), we get \( \frac{5(2^n - 1)}{2 - 1} = 315 \implies 2^n - 1 = 63 \implies 2^n = 64 \implies n = 5 \).
