Question

Difference between CI and SI on rs. 8400 for 2 years at 21 at same rate of interest per year. Find rate of interest

Answer 1

$\textbf{Given:}$

$\textsf{Difference between C.I and S.I on Rs.8400 for 2 years is Rs.21}$

$\textbf{To find:}$

$\textsf{Rate of interest}$

$\textbf{Solution:}$

$\textbf{Formula used:}$

$\textsf{Difference between C.I and S.I for 2 years is}$

$\mathsf{\dfrac{Pr^2}{100^2}}$

$\mathsf{C.I-S.I=Rs.21}$

$\implies\mathsf{\dfrac{Pr^2}{100^2}=21}$

$\implies\mathsf{\dfrac{8400{\times}r^2}{100{\times}100}=21}$

$\implies\mathsf{\dfrac{84{\times}r^2}{100}=21}$

$\implies\mathsf{r^2=\dfrac{21{\times}100}{84}}$

$\implies\mathsf{r^2=\dfrac{100}{4}}$

$\implies\mathsf{r^2=25}$

$\implies\boxed{\mathsf{r=5\%}}$