What is the difference between the compound interest and simple interest on ₹ $4000$ at $5 \%$ per annum for $2$ years?

What will be the compound interest (in ₹) on a sum of ₹ $1875$ after $2$ years if the rate of interest for the first year is $4 \%$ and that for the second year is $8 \%$?

What would be the $C.I.$ obtained on an amount of $Rs. 4800$ at the rate of $5$ $p.c.p.a$ for $3$ years (in $Rs.$)?

What sum will give ₹ $244$ as the difference between simple interest and compound interest at $10 \%$ per annum in $1 \frac{1}{2}$ years,compounded half-yearly?

$A$ sum of money placed at compound interest doubles itself in $5$ years. It will amount to eight times itself at the same rate of interest in (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?