At what rate of compound interest per annum will a sum of Rs. 1200 become Rs. 1348.32 in 2 years?

$$\eqalign{ & {\text{Let}}\,{\text{the}}\,{\text{rate}}\,{\text{be}}\,R\% \,p.a. \cr & {\text{Then}},\,1200 \times {\left( {1 + \frac{R}{{100}}} \right)^2} = 1348.32 \cr & \Rightarrow {\left( {1 + \frac{R}{{100}}} \right)^2} = \frac{{134832}}{{120000}} = \frac{{11236}}{{10000}} \cr & \therefore {\left( {1 + \frac{R}{{100}}} \right)^2} = {\left( {\frac{{106}}{{100}}} \right)^2} \cr & \Rightarrow 1 + \frac{R}{{100}} = \frac{{106}}{{100}} \cr & \Rightarrow R = 6\% \cr} $$