• # question_answer Peter invested a certain sum of money in a simple interest bond whose value grew to Rs. 600 at the end of 6 years, and to Rs. 800 at the end of another 10 years. What was the rate of interest? A)  12%                            B)  16.66%C)  18.67%                       D)  19.25%

(b): Let rate of interest be 'r' sum invested = P $\therefore 600=P\left( 1+\frac{6r}{100} \right).......1$ and  $800=P\left( 1+\frac{10r}{100} \right).......2$ Dividing, $\frac{600}{800}=\frac{1+\frac{6r}{100}}{1+\frac{10r}{100}}$ $\Rightarrow \frac{6}{8}=\frac{3}{4}=\frac{1+\frac{6r}{100}}{1+\frac{10r}{100}}$ Cross multiplying, $3+\frac{30r}{100}=4+\frac{24r}{100}$ $\frac{6r}{100}=1$ $r=\frac{100}{6}=16.66%$