$A$ person invests $Rs. 2,00,000$ at $12 \%$ $p.a.$ for $1$ $year$. If he invests $Rs. 500$ more,he is eligible for $13 \%$ $p.a.$ interest. How much more interest (in $Rs.$) would he receive if he accepted the second option?

At what rate per cent per annum will a sum of money double in $16$ years (in $.25$)?

Mr. Mani invested an amount of ₹ $12000$ at a simple interest rate of $10 \%$ $p.a.$ and another amount at a simple interest rate of $20 \%$ $p.a.$. The total interest earned at the end of one year on the total amount invested was $14 \%$ $p.a.$. Find the total amount (in ₹) invested.

Arun invested a sum of money at a certain rate of simple interest for a period of $4$ years. Had he invested the same sum for a period of $6$ years,the total interest earned by him would have been $50\%$ more than the earlier interest amount. What was the rate of interest per cent per annum?

Ram divided $2189$ into three parts such that the simple interest on them after $1, 2,$ and $3$ years respectively is equal. The rate of simple interest is $4\%$ per annum in all cases. The smallest part is (in $Rs.$):

If ₹ $500$ amounts to ₹ $725$ at $9 \%$ simple interest in some time,what will ₹ $600$ amount (in ₹) to at $11 \%$ in the same time?