What principal will amount (in ₹) to ₹ $15000$ at $10 \%$ per annum in $5$ years?

The annual payment of $Rs. 160$ in $5 \, \text{years}$ at $5 \%$ per annum simple interest will discharge a debt of (in $Rs.$):

An automobile financier claims to be lending money at simple interest,but he includes the interest every six months for calculating the principal. If he is charging an interest of $10 \%$ per annum,the effective rate of interest (in $\%$) becomes:

$A$ sum of money becomes $\frac{8}{5}$ of itself in $5$ $years$ at a certain rate of interest. The rate per cent per annum is

$A$ certain sum doubles in $7$ years at simple interest. The same sum under the same interest rate will become $4$ times in how many years?

Mrs. Sushma lent out an amount of $Rs. 3000$ at $4 \%$ p.a. and some other amount at $5 \%$ p.a. If at the end of the year she received $Rs. 138$ as total interest,what amount (in $Rs.$) did she lend out at $5 \%$ p.a.?