The compound interest on Rs. 30000 at 7% per annum is Rs. 4347. The period (in years) is = ?

The compound interest on Rs. 30000 at 7% per annum is Rs. 4347. The period (in years) is = ? Correct Answer 2 years

$$\eqalign{ & {\text{Amount = Rs}}{\text{. }}\left( {30000 - 4347} \right) \cr & {\text{Amount = Rs}}{\text{. }} 34347 \cr & {\text{Let the time be }}n{\text{ years}} \cr & {\text{Then,}} \cr & {\text{30000}}{\left( {1 + \frac{7}{{100}}} \right)^n} = 34347 \cr & \Leftrightarrow {\left( {\frac{{107}}{{100}}} \right)^n} = \frac{{34347}}{{30000}} \cr & \Leftrightarrow {\left( {\frac{{107}}{{100}}} \right)^n} = \frac{{11449}}{{10000}} = {\left( {\frac{{107}}{{100}}} \right)^2} \cr & \therefore n = {\text{ 2 years}} \cr} $$

Related Questions

Find the interest obtained after 3 years on a sum which is invested on compound interest at the rate of R% per annum? Statement I: If Rs. 32000 is invested on simple interest at the rate of R% per annum, then Rs. 4480 interest is obtained in 2 years. Statement II: The difference of simple and compound interest on the sum is Rs. 245 after 2 years when invested at same rate.