The difference between simple and compound interest on a sum of $10000$ is $64$ for $2$ years. Find the rate of interest. (in $\%$)

The difference between simple interest and compound interest on a certain sum for $3$ years at $5 \%$ per annum is ₹ $122$. Find the sum (in ₹).

If in a certain number of years,₹ $3000$ amounts to ₹ $4320$ at compound interest,in half that time ₹ $3000$ will amount to (in ₹):

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

$A$ man gave $50 \%$ of his savings of ₹ $84,100$ to his wife and divided the remaining sum among his two sons $A$ and $B$ of $15$ and $13$ years of age respectively. He divided it in such a way that each of his sons,when they attain the age of $18$ years,would receive the same amount at $5 \%$ compound interest per annum. The share of $B$ was (in ₹):

$A$ sum of $Rs. 1000$ after $3 \, \text{years}$ at compound interest becomes a certain amount that is equal to the amount that is the result of a $3 \, \text{year}$ depreciation from $Rs. 1728$. Find the difference between the rates (in $\%$) of $C.I.$ and depreciation? (Given $C.I.$ is $10 \% \, p.a.$)