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InterviewSolution
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`S_(10)` is the sum of first 10 terms of a GP and `S_5` is the sum of the first 5 terms of the same GP. If `(S_(10))/(S_5)= 244`, then find the common ratio.A. 3B. 4C. 5D. 2 |
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Answer» Correct Answer - A `(S_(10))/(S_5) = (((a*(r^(10) -1)))/((r-1)))/(((a(r^(5)-1)))/(r-1))` or, `(S_(10))/(S_5) = (r^(10) -1)/(r^(5)-1) = r^(5) + 1` `" "(S_(10))/(S_5) = ((r^(5)-1)^(2) + 2r^(5)-2)/(r^(5)-1)` `244 = ((r^(5)-1)[r^(5)-1=2])/((r^(5)-1))rArr 244 = r^(5) +1` or, `r^(5) = 243 rArr r = 3`. |
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