$A$ sum of ₹ $1,550$ is lent out in two parts,one at $8 \%$ and another at $6 \%$. If the total annual income is ₹ $106$,find the money lent at each rate.

An automobile financier claims to be lending money at simple interest,but he includes the interest every six months for calculating the principal. If he is charging an interest of $10 \%$ per annum,the effective rate of interest becomes (in $\%$):

$A$ sum of $Rs. 2540$ is lent out in two parts,one at $12 \%$ and the other at $12.5 \%$. If the total annual return on the total money invested is $Rs. 312.42$,find the money (in $Rs.$) lent at $12 \% \text{ p.a.}$

Arun lends ₹ $20,000$ to two of his friends. He gives ₹ $12,000$ to the first at $8 \%$ p.a. simple interest. Arun wants to make a profit of $10 \%$ on the whole. The simple interest rate $\%$ at which he should lend the remaining sum of money to the second friend is

$A$ sum of money doubles itself in $8$ years. In how many years will it treble?

$A$ 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?