A sum at R% compound interest doubles in 3 years. In 9 years it will be k times of the original principal. What is the value of k? A. 9 B. 8 C. 6 D. 7 Answer Workspace Report Discuss Answer with explanation Answer: Option B Explanation A = P[1+ r/100]^n A == 2P in 3 years 2P = P[1 + r/100]^3 [dividing by ‘p’ both LHS and RHS] 2 = [1 + r/100]^3 …….(i) kP = P[1 + r/100]^9 k = [1 + r/100]^9 ……(ii) On cubing the eq. (i) 2^3 = { [1 + r/100]^3}^3 8 = [1 + r/100]^9 …..(iii) COMPARING eq.(ii) & eq.(iii) k = 8 Hence, 8 times Workspace
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