The value of a machine depreciates at the rate of $12\%$ per annum. It was purchased $3$ years ago. Its present value is $Rs. 29644.032$. What was the purchase price (in $Rs.$) of the machine?

What would be the $C.I.$ on $Rs. 17500$ at the rate of $12$ $p.c.p.a.$ after $2$ years (in $Rs.$)?

If $64000$ is deposited at $5 \%$ compound interest for a period of $18$ months,interest being compounded half-yearly,find the amount.

$A$ sum of money doubles in $3$ years at compound interest,compounded annually. It will become $4$ times of itself in: (in $years$)

$A$ man borrows money at $3 \%$ per annum interest payable yearly and lends it immediately at $5 \%$ interest (compound) payable half-yearly and thereby gains ₹ $330$ at the end of the year. The sum borrowed (in ₹) is

$A$ man borrows ₹ $4000$ from a bank at $7 \frac{1}{2} \%$ compound interest. At the end of every year,he pays ₹ $1500$ as part repayment of the loan and interest. How much does he still owe to the bank after three such instalments (in ₹)?