The simple interest on a sum for $8$ years is ₹ $47500$. The rate of interest is $10 \%$ per annum for the first $5$ years and $15 \%$ per annum for the next $3$ years. What is the value (in ₹) of the sum?

$A$ certain amount earns simple interest of ₹ $1,750$ after $7$ years. Had the interest rate been $2 \%$ more per annum,how much more interest would it have earned (in ₹)?

What amount (in $Rs.$) would a man have received on a principal of $Rs. 4000$ after $2$ years at a simple interest rate of $5$ $p.c.p.a.$?

The simple interest accrued on a certain principal is ₹ $1200$ in $4$ years at the rate of $8 \%$ per annum. What would be the simple interest (in ₹) accrued on thrice of that principal at the rate of $6 \%$ per annum in $3$ years?

Two equal sums were lent at simple interest for $4$ years and for $3$ years respectively. The rate of interest in the latter case was $3 \%$ higher than that of the former case,but the amount in each was $Rs. 1088$. Find the rate of interest (in $\%$) of the former case?

The population of Mumbai increases by $5 \%$ per annum. Its population was $100000$ in $2004$. What was its population after $3$ years?