What time (in years) is taken by a sum of $Rs. 7000$ to become $Rs. 10500$ at the rate of $5 \%$ per annum simple interest?

Deepak lent ₹ $8800$ to Jaichand for $13$ $years$ and ₹ $5500$ to another person for $12$ $years$ at the same rate of simple interest. He received ₹ $14432$ in total as interest from both. The rate of interest (in $\%$) per annum is:

$A$ money lender lends ₹ $400$ for $3$ $years$ to a person and ₹ $500$ for $4$ $years$ to another person at the same rate of simple interest. If altogether he receives ₹ $160$ as interest,what is the rate of interest per annum (in $\%$)?

$A$ certain sum of money amounts to ₹ $2200$ at $5 \%$ $p.a.$ rate of interest,and ₹ $2320$ at $8 \%$ interest in the same period of time. The period of time (in years) is:

Arun gives his wife Asha a birthday gift,giving her each year a number of rupees equal to the number of years of her age. If her birthday falls on $August \, 8$,what sum must be placed at simple interest at $7 \%$ on $January \, 1$,before she is $42$,in order to raise the required sum (in $Rs.$)?

Ravi invested a total amount of $Rs. 65,000$ in three different schemes $A, B, C$ with rates of interest $12\%$,$16\%$,and $18\%$ per annum respectively,and earned a total interest of $Rs. 10,180$ in one year. If the amount invested in scheme $A$ is $72\%$ of the amount invested in scheme $C$,then what was the amount (in $Rs.$) invested in scheme $B$ (in $,000$)?