If a sum of money placed at compound interest,compounded annually,doubles itself in $5$ years,then the same amount of money will be $8$ times of itself in how many years?

An amount of ₹ $8000$ was deposited at simple interest for $3$ years at $7.5$ $\%$ per annum. How much more would have been gained (in ₹) had it been deposited at the same rate per cent compound interest?

If the difference between the simple and the compound interest earned on a sum of money at the rate of $5$ $p.c.p.a.$ for $2$ $years$ is $Rs. 16$,find the principal (in $Rs.$).

The difference between the compound interest and simple interest on a certain sum at $5 \%$ per annum for $2$ years is ₹ $1.50$. The sum is (in ₹):

$A$ sum of ₹ $3,200$ invested at $10 \%$ per annum compounded quarterly amounts to ₹ $3,362$. Compute the time period (in years).

What is the difference between the simple and the compound interest (in ₹) on ₹ $7,300$ at the rate of $6$ $p.c.p.a.$ in $2$ years?