Question

Ishita invested a sum of Rs 12000 at 5% per annum compound interest. She received an amount of Rs 13230 after n years. Find the value of n.

Answer 1

$$\begin{gathered} \mathrm{A}=\mathrm{P}{\left(1+\frac{\mathrm{R}}{100}\right)}^{\mathrm{n}} \\ 13,230=12,000{\left(1+\frac{5}{100}\right)}^{\mathrm{n}} \\ {\left(1.05\right)}^{\mathrm{n}}=\frac{13,230}{12,000} \\ {\left(1.05\right)}^{\mathrm{n}}=1.1025 \\ {\left(1.05\right)}^{\mathrm{n}}={\left(1.05\right)}^2 \\ \mathrm{On}\mathrm{comparing}\mathrm{both}\mathrm{the}\mathrm{sides},\mathrm{we}\mathrm{get}: \\ \mathrm{n}=2 \\ \mathrm{Thus},\mathrm{the}\mathrm{value}\mathrm{of}\mathrm{n}\mathrm{is}\mathrm{two}\mathrm{years}. \end{gathered}$$