In how much time an investment of Rs. 50,000 at the rate of 5% simple interest would be doubled, if the…

In the first 10 years the simple interest is $50000\times0.05\times10=25000$, and adding it makes the principal ₹75,000. A further ₹25,000 is needed to reach ₹1,00,000; on ₹75,000 at 5% the yearly interest is 3750, so this takes $\frac{25000}{3750}=6\frac{2}{3}$ years. The total time is $10+6\frac{2}{3}=16\frac{2}{3}$ years, whereas without adding the interest after 10 years doubling would take 20 years.