$A$ sum of ₹ $15000$ deposited at compound interest becomes double after $5$ $years$. After $20$ $years$,it will become (in ₹):

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?

The compound interest on $₹ 1,800$ at $10 \%$ per annum for a certain period of time is $₹ 378$. Find the time in years.

The difference between the compound interest and the simple interest accrued on an amount of ₹ $18000$ in $2$ years was ₹ $405$. What was the rate of interest per cent per annum?

The simple interest accrued on a certain principal is ₹ $2,000$ in five years at the rate of $4$ percent $p.a.$ What would be the compound interest (in ₹) accrued on the same principal at the same rate in two years?

$A$ sum of $Rs. 8448$ is to be divided between $X$ and $Y$ who are respectively $18$ and $19 \,yr$ old,in such a way that if their shares be invested at $6.25 \%$ per annum at compound interest,they will receive equal amounts on attaining the age of $21 \,yr$. The present share of $X$ is (In $Rs.$)