If a sum of ₹ $9$ is lent to be paid back in $10$ equal monthly instalments of ₹ $1$ each,then the rate of interest is

What is the interest (in $Rs.$) received on a principal of $Rs. 450$ for $2$ years, if the interest received on $Re. 1$ after $4$ years at the same rate of simple interest is $Rs. 0.40$?

The simple interest accrued on an amount of $Rs. 2500$ at the end of six years is $Rs. 1875$. What would be the simple interest (in $Rs.$) accrued on an amount of $Rs. 6875$ at the same rate and same period?

$A$ sum of money invested at simple interest for two years at $5 \% \text{ p.a.}$ amounted to $Rs. 2750$. The rate at which the sum should have been invested to get $Rs. 300$ as interest after two years would be (in $\%$)?

Kavita invested $\frac{1}{3}$ of her money at $4 \% \text{ p.a.}$,$\frac{1}{4}$ at $3 \% \text{ p.a.}$,and the rest at $5 \% \text{ p.a.}$ She received an annual interest of $Rs. 500$ on her money. Find the total money invested (in $Rs.$).

If the simple interest on a certain sum of money after $6 \frac{1}{4}$ years is $\frac{3}{8}$ of the principal,then the rate of interest (in $\%$) per annum is