There is a $40 \%$ increase in an amount in $8$ years at simple interest. What will be the compound interest (in rupees) on ₹ $30000$ after $2$ years at the same rate?

The compound interest (in ₹) on ₹ $2000$ at $5 \%$ per annum,compounded yearly,for $2$ years is

$A$ sum of money at compound interest doubles itself in $15$ years. It will become eight times of itself in (in $years$):

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.

The difference between compound interest and simple interest on a sum for $2$ years at $10 \%$ per annum,when the interest is compounded annually,is ₹ $20$. If the interest were compounded half-yearly,the difference in the two interests (in ₹) will be:

Raghu invested a certain sum in Scheme $X$ for $4$ years. Scheme $X$ offers simple interest at $12\%$ per annum for the first two years and compound interest (compounded annually) at $20\%$ per annum for the next two years. The total interest earned by him after $4$ years is $₹ 11016$. What was the sum (in $₹$) invested by Raghu in Scheme $X$?