In an examination,$35 \%$ of the students passed and $455$ failed. How many students appeared for the examination?

There is a ratio of $5:4$ between two numbers. If $40\%$ of the first number is $12$,then what would be $50\%$ of the second 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.

What percent of $7.2 \,kg$ is $18 \,g$?

In a class of $50$ students and $5$ teachers,each student received sweets equal to $12 \%$ of the total number of students,and each teacher received sweets equal to $20 \%$ of the total number of students. How many sweets were there in total?

Two jars contain equal quantities of $40 \%$ alcohol. Swati changed the concentration of the first jar to $50 \%$ by adding extra quantity of pure alcohol. Sonali changed the concentration of the second jar to $50 \%$ by replacing a certain quantity of the solution with pure alcohol. By what percentage is the quantity of alcohol added by Swati more than that replaced by Sonali?