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

What sum of money (in $Rs.$) at compound interest will amount to $Rs. 5305.53$ in $3$ years,if the rate of interest is $1 \%$ for the first year,$2 \%$ for the second year,and $3 \%$ for the third year?

The compound interest accrued on an amount at the end of $3$ $years$ at $15$ $p.c.p.a.$ is $Rs. 6500.52$. What is the principal amount (in $Rs.$)?

Rohit invested some amount at the rate of $6\%$ per annum and at the end of $3$ years he received ₹ $8730$ as simple interest. How much compound interest (in ₹) will he receive on the same amount and same rate of interest after $2$ years?

If the difference between $S.I.$ and $C.I.$ for $2$ years on a sum of money lent at $5 \%$ per annum is $₹ 6$,then the sum is:

The compound interest (in ₹) on ₹ $800$ for $2 \frac{1}{2}$ years at $5 \%$ per annum is: