A class has $175$ students. The following data shows the number of students obtaining one or more subjects. Mathematics $100$, Physics $70$, Chemistry $40$; Mathematics and Physics $30$, Mathematics and Chemistry $28$, Physics and Chemistry $23$; Mathematics, Physics and Chemistry $18$. How many students have offered Mathematics alone

Let $X = \{ $ Ram ,Geeta, Akbar $\} $ be the set of students of Class $\mathrm{XI}$, who are in school hockey team. Let $Y = \{ {\rm{ }}$ Geeta, David, Ashok $\} $ be the set of students from Class $\mathrm{XI}$ who are in the school football team. Find $X \cup Y$ and interpret the set.

There are $200$ individuals with a skin disorder, $120$ had been exposed to the chemical $C _{1}, 50$ to chemical $C _{2},$ and $30$ to both the chemicals $C _{1}$ and $C _{2} .$ Find the number of individuals exposed to

Chemical $C_{1}$ or chemical $C_{2}$

In a classroom, one-fifth of the boys leave the class and the ratio of the remaining boys to girls is $2: 3$. If further $44$ girls leave the class, then class the ratio of boys to girls is $5: 2$. How many more boys should leave the class so that the number of boys equals that of girls?

Out of all the patients in a hospital $89\, \%$ are found to be suffering from heart ailment and $98\, \%$ are suffering from lungs infection. If $\mathrm{K}\, \%$ of them are suffering from both ailments, then $\mathrm{K}$ can not belong to the set :

A group of $40$ students appeared in an examination of $3$ subjects - Mathematics, Physics  Chemistry. It was found that all students passed in at least one of the subjects, $20$ students passed in Mathematics, $25$ students passed in Physics, $16$ students passed in Chemistry, at most $11$ students passed in both Mathematics and Physics, at most $15$ students passed in both Physics and Chemistry, at most $15$ students passed in both Mathematics and Chemistry. The maximum number of students passed in all the three subjects is___________.