If ₹ $640$ amounts to ₹ $832$ in $2$ years,what will ₹ $860$ amount to in $4$ years at the same rate of interest per annum (in ₹)?

$A$ sum was put at simple interest at a certain rate for $2$ years. Had it been put at $1 \%$ higher rate,it would have fetched ₹ $24$ more. The sum is (in ₹):

At what rate per cent of simple interest will a sum of money double itself in $12$ years?

Anil invested an amount for $3$ $years$ at a simple interest rate of $9$ $p.c.p.a.$ He got an amount of $Rs. 19050$ at the end of $3$ $years.$ What principal amount (in $Rs.$) did he invest?

The population of a city increases at the rate of $5 \%$ $p.a.$ If the present population of the city is $370440$,then what was its population (in $lakh$) $3$ years ago?

$A$ 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 ₹)?