The percentage of metals in a mine of lead ore is $60 \%$. Now, the percentage of silver is $3/4 \%$ of the metals and the rest is lead. If the mass of ore extracted from this mine is $8000 \, kg$, what is the mass (in $kg$) of lead?

If $20 \%$ of $a = b$,then $b \%$ of $20$ is the same as: (in $\%$ of $a$)

An empty fuel tank of a car was filled with $A$ type petrol. When the tank was half-empty,it was filled with $B$ type petrol. Again when the tank was half-empty,it was filled with $A$ type petrol. When the tank was half-empty again,it was filled with $B$-type petrol. What is the percentage of $A$ type petrol at present in the tank?

In a school there are $1500$ students,$44 \%$ of whom are girls. The monthly fee of each boy is $₹ 540$ and the fee of each girl is $25 \%$ less than that of a boy. What is the sum of the monthly fees of all the boys and girls?

Two numbers are respectively $12 \frac{1}{2} \%$ and $25 \%$ more than a third number. The first number as a percentage of the second number is

$A$ scored $30\%$ marks and failed by $15$ marks. $B$ scored $40\%$ marks and obtained $35$ marks more than that required to pass. The pass percentage is: (in $\%$)