$\frac{3}{4}$ of $\frac{2}{3}$ of $\frac{1}{5}$ of a number is $249.6$. What is $50\%$ of that number?

How many students passed in first class?
Statements:
$I$. $85 \%$ of the students who appeared in the examination have passed either in first class,second class,or pass class.
$II$. $750$ students have passed in second class.
$III$. The number of students who passed in pass class is $28 \%$ of those who passed in second class.

$A$ person's salary has increased from $Rs. 7200$ to $Rs. 8100$. What is the percentage increase in his salary (in $\%$)?

$A$ spider climbed $62 \frac{1}{2} \%$ of the height of the pole in one hour and in the next hour it covered $12 \frac{1}{2} \%$ of the remaining height. If the height of the pole is $192 \, m$,then the distance climbed in the second hour is:

Christy donated $10 \%$ of his income to an orphanage and deposited $20 \%$ of the remainder in his bank. If he has now $Rs$ $7200$ left,what is his income?

$0.15 \%$ of $33 \frac{1}{3} \%$ of $₹ 10000$ is