On a certain Principal, if the Simple Interest for two years is $\text{Rs }4800$ and Compound Interest for the two years is $\text{Rs }5088$, what is the rate of Interest?

Given:Simple Interest (SI) for 2 years = $\text{Rs }4800$ Compound Interest (CI) for 2 years = $\text{Rs }5088$ SI is uniform for every year, so SI for 1st year = $\frac{4800}{2}=\text{Rs }2400$.For the first year, CI is equal to SI, so CI for 1st year = $\text{Rs }2400$.The difference between CI and SI over 2 years arises because interest is earned on the first year's interest in compound interest:
$$\text{Difference (D)}=\text{CI}-\text{SI}=5088-4800=\text{Rs }288$$
This $\text{Rs }288$ is the interest earned on the first year's interest ($\text{Rs }2400$) for 1 year.
$$\text{Rate of Interest }(R)=\frac{\text{Difference}}{\text{SI of 1st year}}\times 100\%$$
$$R=\frac{288}{2400}\times 100\%=\frac{288}{24}\%=12\%$$