$A$ certain sum of money at compound interest grows up to ₹ $12960$ in $2$ years and up to ₹ $13176$ in $3$ years. Find the rate per cent per annum.

Which of the statements given below are sufficient to answer the following question?
What is the rate of interest per annum on an investment of $Rs. 800$?
$(I)$ The income from $S.I.$ at the end of $3$ years at the same rate of interest is $19$.
$(II)$ $C.I.$ is $15.76$ more than $S.I.$ on the same sum and same rate in $2$ years.

Suneeta borrowed a certain sum from Reena for $2 \,yr$ at simple interest. Suneeta lent this sum to Venu at the same rate for $2 \,yr$ at compound interest. At the end of $2 \,yr$,she received $Rs. 110$ as compound interest but paid $Rs. 100$ as simple interest. Find the sum and the rate of interest.

What would be the $C.I.$ obtained on an amount of $12500$ at the rate of $12 \, p.c.p.a.$ after $2$ years (in $Rs.$)?

In a certain number of years,a sum of money doubles itself at $6 \frac{1}{4} \%$ simple interest per annum. The required time (in $years$) is:

The compound interest (in ₹) on ₹ $5,000$ for $3$ years at $10 \%$ per annum will amount to: