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

Hemant makes a fixed deposit of $Rs. 20000$ in Bank of India for a period of $3 \,yr$. If the rate of interest is $13 \%$ $SI$ per annum charged half-yearly,what amount (in $Rs.$) will he get after $42 \,months$?

The rate of interest on a sum of money is $4 \%$ per annum for the first $2$ years,$6 \%$ p.a. for the next $4$ years,and $8 \%$ p.a. for the period beyond $6$ years. If the simple interest accrued by the sum for a total period of $9$ years is ₹ $1120$,then the sum (in ₹) is:

In what time will ₹ $8100$ produce the same income at $3 \%$ as ₹ $225$ in $4$ years at $3 \%$?

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?

$A$ sum of money lent out at simple interest amounts to $Rs. 720$ after $2$ years and $Rs. 1020$ after a further period of $5$ years. Find the principal (in $Rs.$).