$A$ certain sum doubles in $7$ years at simple interest. The same sum under the same interest rate will become $4$ times in how many years?

$A$ man invested $\frac{1}{3}$ of his capital at $7 \%$,$\frac{1}{4}$ at $8 \%$,and the remainder at $10 \%$. If the annual income is ₹ $561$,the capital (in ₹) is:

$A$ sum of money will double itself in $16$ years at simple interest at an yearly rate of (in $\%$):

Arun lends ₹ $20,000$ to two of his friends. He gives ₹ $12,000$ to the first at $8 \%$ p.a. simple interest. Arun wants to make a profit of $10 \%$ on the whole. The simple interest rate $\%$ at which he should lend the remaining sum of money to the second friend is

If the simple interest on a certain sum of money is ₹ $256$ and the rate of interest per annum equals the number of years,then the rate of interest (in $\%$) is:

The simple interest accrued on an amount of ₹ $22,500$ at the end of four years is ₹ $10,800$. What would be the compound interest accrued on the same amount (in ₹) at the same rate of interest at the end of two years?