Rama mixes $20 \%$ of kerosene to his petrol and then he sells the whole mixture at the price of petrol. If the cost price of the kerosene is $40 \%$ of the $CP$ of petrol,what is the net profit percentage (in $\%$)?

In the first alloy,zinc and copper are in the ratio $1:2.$ In the second alloy,the same elements are in the ratio $2:3.$ If these two alloys are mixed to form a new alloy in which the two elements are in the ratio $5:8,$ the ratio of these two alloys in the new alloy is

In an examination out of $480$ students,$85 \%$ of the girls and $70 \%$ of the boys passed. How many boys appeared in the examination if the total pass percentage was $75 \% ?$

In what ratio must water be mixed with milk to gain $16 \%$ on selling the mixture at cost price?

$100$ $litres$ of a mixture contains $20 \%$ water and the rest is milk. The amount of milk that must be added so that the resulting mixture contains $87.5 \%$ milk is (in $litres$):

The ratio of the quantities of an acid and water in a mixture is $1:3$. If $5$ $litres$ of acid is further added to the mixture,the new ratio becomes $1:2$. The quantity of the new mixture in litres is