Bidyut Guha Thakurta and Amitava Mitra Solutions for Exercise 1: EXERCISE 1

Bikasbabu fixed $₹12000$ for $3$ years in United Bank at $10\%$ simple interest. But for his daughter's marriage he withdraws the total amount together with the interest after $2$ years. For this he got $₹1920$ less than what he would get at the end of $3$ years. What was the rate of his interest?

A sum of money double itself in $20$ years. The rate of interest _____$\%$

Monthly interest of $₹500$ is $₹5$. Then the rate of interest is $10\%$ per annum.

At $r\%$ rate of simple interest per annum, $₹P$ amounts to $₹P\left(1+\frac{rt}{100}\right)$ in $t$ years.

If the ratio of a principal and its interest in $2$ years be $10:1$, then the rate of simple interest per annum is $5\%$.

If the rate of interest is $5\%$ per annum, then the ratio of a principal and its interest in $2\frac{1}{2}$ years is $10:1$.

A certain sum of money will be doubled itself in $20$ years at $10\%$ simple interest per annum.

If the interest of a sum of money at the rate of $10\%$ per annum be $\frac{2}{3}\mathrm{rd}$ of the amount, then the time is $20$ years.