Question

The Difference between the SI and the CI payable half yearly on a certain sum of
money at 16% per annum for 1 year in Rs640/- . what is the principal?​

Answer 1

Answer:

take principal=x

then,

$x(1 + \frac{8}{100} ) {}^{2} - \frac{x \times 8 \times 2}{100} = 640$

$x( \frac{27}{25} \times \frac{27}{25} ) - \frac{4x}{25} = 640$

$\frac{729x}{625} - \frac{4x}{25} = 640$

$729x - 4x = 640 \times 625 \times 25$

$725x = 1000000$

$x = 13793.1$