During the first year,the population of a village is increased by $5 \%$ and in the second year it is diminished by $5 \%$. At the end of the second year,its population was $47880$. What was the population at the beginning of the first year?

In how many years will ₹ $150$ produce the same interest at $8 \%$ per annum as ₹ $800$ produces in $3$ years at $4 \frac{1}{2} \%$ per annum?

Nitin borrowed some money at the rate of $6 \% \text{ p.a.}$ for the first three years,$9 \% \text{ p.a.}$ for the next five years,and $13 \% \text{ p.a.}$ for the period beyond eight years. If the total interest paid by him at the end of eleven years is ₹ $8,160$,the money borrowed by him was:

The simple interest on ₹ $500$ at $6 \%$ per annum from $May$ $3^{rd}$ to $July$ $15^{th}$ in the same year is (in ₹):

Simple interest received by a person in $10$ $years$ on a principal of ₹ $9500$ is $130 \%$ of the principal. What is the rate of interest (in $\%$) per annum?

Bindu lends $Rs. 10000$ in four parts to her friends. If she gets $8 \%$ on $Rs. 2000$,$7.5 \%$ on $Rs. 4000$ and $8.5 \%$ on $Rs. 1400$,what percent must she get for the remainder,if the average interest is $8.13 \%$?