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

Let U be universal set of all the students of Class XI of a coeducational school and A be the set of all girls in Class XI. Find A′.

Let A be the set of all 50 students of Class X in a school Let f: A to N be function defined by f(x) = roll number of the student x. Show that f in one-one but not onto.

The marks obtained in mathematics by 30 students of Class X of a certain school are given in table the below. Find the mean of the marks obtained by the students.

Suppose A is the set of students in your class who were absent on Tuesday and B the set of students who were absent on Wednesday. Then, A = {Roja, Ramu, Ravi} and B = {Ramu, Preethi, Haneef} Now, we want to find K, the set of students who were absent on either Tuesday or Wednesday. Then, does Roja in Κ? Ramu in Κ? Ravi in Κ? Haneef in Κ? Preeti in Κ? Akhila in Κ?

Let A be the set of all students of a boys school. Show that the relation R in A given by R = {(a,b):a is sister of b} is the empty relation and R' ={(a,b): the difference between heights of a and b is less than 3 meters } is the universal relation.

15 students of Class-X took part in a science quiz. If the number of boys is 5 more than the number of girls then, find the number of boys and the number of girls who took part in the quiz.

There are 40 students in Class X of a school of whom 25 are girls and 15 are boys. The class teacher has to select one student as a class representative. She writes the name of each student on a separate cards, the cards being identical . Then she puts cards in a box and stirs them throughly. She then draws one card from the box.What is the probability that the name written on the card is the name of a boy?

There are 40 students in Class X of a school of whom 25 are girls and 15 are boys. The class teacher has to select one student as a class representative. She writes the name of each student on a separate cards, the cards being identical . Then she puts cards in a box and stirs them thoroughly. She then draws one card from the box.What is the probability that the name written on the card is the name of a girl

10 students of Class-X took part in a mathematics quiz. If the number of girls in 4 more than the number of boys then, find the number of boys and the number of girls who took part in the quiz.\