$A$ certain sum of money invested at compound interest becomes $1.44$ times of itself in $2$ years. If twice this sum were lent at simple interest, in how many years would it double itself?

The simple interest on a certain sum of money for $3$ years at $8 \%$ per annum is half the compound interest on ₹ $4000$ for $2$ years at $10 \%$ per annum. The sum placed on simple interest (in ₹) is

$A$ sum of money doubles in $3$ years at compound interest,compounded annually. It will become $4$ times of itself in: (in $years$)

The difference between the $S.I.$ and $C.I.$ obtained on a principal amount at $5$ $p.c.p.a.$ after $2$ years is $Rs. 35$. What is the principal amount (in $Rs.$)?

$A$ sum of money placed at compound interest doubles itself in $5 \, \text{years}$. It will amount to eight times itself at the same rate of interest in (in $\text{years}$):

₹ $6,100$ was partly invested in Scheme $A$ at $10 \%$ p.a. compound interest (compounded annually) for $2$ years and partly in Scheme $B$ at $10 \%$ p.a. simple interest for $4$ years. Both the schemes pay equal interests. How much was invested (in ₹) in Scheme $A$?