Selina Textbook Solutions: Sets | Mathematics Class 6 ICSE PDF Download

 Page 1


IMPORTANT POINTS 
In our day-to-day life we often speak or hear about different types of collections. 
Such as : 
(i) A collection of stamps. 
(ii) A collection of toys : 
(iii) A collection of books, etc. 
In the same way, we have different types of groups made for different activities. 
Such as : 
(i) A group of boys playing hockey. 
(ii) A group of girls playing badminton. 
(iii) A group of students going for picnic, etc. 
In mathematics, a collection of particular things or a group of particular objects is called 
a set. 
1. Definition of a Set : A set is a collection of well-defined objects. 
2. Meaning of “Well-Defined” : Well- defined means, it must be absolutely clear 
that which object belongs to the set and which does not. 
3. Elements (or, members) of a set : The objects used to form a set are called its 
elements or its members. 
Keep in Mind : 
? The pair of curly braces { } denotes a set. 
? The Greek letter Epsilon ‘ e ’ is used for the words “belongs to”, “is an 
element of, etc. 
p e A will be be read as “p belongs to set A” or “p is an element of set A”. 
In the same way ; q e A, r e A, s e a. and t e A. 
The symbol ‘e not’ stands for “does not belong to” also for “is not an element 
of. 
a e not A will be read as “a does not belong to set A” or “a is not an element 
of set A”. 
4. Properties of a set : 
? The change in order of writing the elements does not make any change in 
the set. 
? If one or many elements of a set are repeated, the set remains the same. 
5. Notation (Representation) of a set : 
? Description method : In this method, a well-defined description about the 
elements of the set is made. 
? Roster or Tabular Method : In this method, the elements (members) of a set 
are written inside a pair of curly braces and are separated by commas. 
? Rule or Set Builder Method : In this method, actual elements of the set are 
not listed but a rule or a statement or a formula, in the briefest possible way, 
is written inside a pair of curly braces. 
EXERCISE 10(A) 
Page 2


IMPORTANT POINTS 
In our day-to-day life we often speak or hear about different types of collections. 
Such as : 
(i) A collection of stamps. 
(ii) A collection of toys : 
(iii) A collection of books, etc. 
In the same way, we have different types of groups made for different activities. 
Such as : 
(i) A group of boys playing hockey. 
(ii) A group of girls playing badminton. 
(iii) A group of students going for picnic, etc. 
In mathematics, a collection of particular things or a group of particular objects is called 
a set. 
1. Definition of a Set : A set is a collection of well-defined objects. 
2. Meaning of “Well-Defined” : Well- defined means, it must be absolutely clear 
that which object belongs to the set and which does not. 
3. Elements (or, members) of a set : The objects used to form a set are called its 
elements or its members. 
Keep in Mind : 
? The pair of curly braces { } denotes a set. 
? The Greek letter Epsilon ‘ e ’ is used for the words “belongs to”, “is an 
element of, etc. 
p e A will be be read as “p belongs to set A” or “p is an element of set A”. 
In the same way ; q e A, r e A, s e a. and t e A. 
The symbol ‘e not’ stands for “does not belong to” also for “is not an element 
of. 
a e not A will be read as “a does not belong to set A” or “a is not an element 
of set A”. 
4. Properties of a set : 
? The change in order of writing the elements does not make any change in 
the set. 
? If one or many elements of a set are repeated, the set remains the same. 
5. Notation (Representation) of a set : 
? Description method : In this method, a well-defined description about the 
elements of the set is made. 
? Roster or Tabular Method : In this method, the elements (members) of a set 
are written inside a pair of curly braces and are separated by commas. 
? Rule or Set Builder Method : In this method, actual elements of the set are 
not listed but a rule or a statement or a formula, in the briefest possible way, 
is written inside a pair of curly braces. 
EXERCISE 10(A) 
Question 1. 
State whether or not the following elements form a set; if not, give reason: 
(i) All easy problems in your text book. 
(ii) All three sided figures. 
(iii) The first five counting numbers. 
(iv) All the tall boys of your class. 
(v) The last three days of the week. 
(vi) All triangles that are difficult to draw. 
(vii) The first three letters of the English alphabet. 
(viii) All tasty fruits. 
(ix) All clever boys of class 6. 
(x) All good schools in Delhi. 
(xi) All the girls in your class, whose heights are less than your height. 
(xii) All the boys in your class, whose heights are more than your height. 
(xiii) All the problems in your Mathematics book, which are difficult for Amit. 
Solution: 
(i) No; some problems may be easy for one person but may be difficult to some other 
person. Objects are not well- defined. 
(ii) Yes. 
(iii) Yes. 
(iv) No; it is not mentioned that the boys must be taller than which boy. If we consider 
three boys A, B and C; boy B can be taller than A but not necessarily taller than C. 
(v) Yes 
(vi) No; it may be difficult for one boy to draw a given triangle but to some other boy it 
may be easy to draw the same triangle. 
(vii) Yes 
(viii) No; a fruit may be tasty for one person and may not be tasty to other person / 
persons. 
(ix) No; clever in what respect and from whom out of six ? 
(x) No; all the people can not find the same schools as good as others said. So, the 
objects are not well-defined. 
(xi) Yes 
(xii) Yes 
(xiii) Yes. 
EXERCISE 10(B) 
Question 1. 
If set A = {2, 3, 4, 5, 6}, state which of the following statements arc true and which are 
false : 
(i) 2 ? A 
(ii) 5, 6 ? A 
(iii) 3, 4, 7 ? A 
(iv) 2, 8 ? A 
Solution: 
(i) True 
Page 3


IMPORTANT POINTS 
In our day-to-day life we often speak or hear about different types of collections. 
Such as : 
(i) A collection of stamps. 
(ii) A collection of toys : 
(iii) A collection of books, etc. 
In the same way, we have different types of groups made for different activities. 
Such as : 
(i) A group of boys playing hockey. 
(ii) A group of girls playing badminton. 
(iii) A group of students going for picnic, etc. 
In mathematics, a collection of particular things or a group of particular objects is called 
a set. 
1. Definition of a Set : A set is a collection of well-defined objects. 
2. Meaning of “Well-Defined” : Well- defined means, it must be absolutely clear 
that which object belongs to the set and which does not. 
3. Elements (or, members) of a set : The objects used to form a set are called its 
elements or its members. 
Keep in Mind : 
? The pair of curly braces { } denotes a set. 
? The Greek letter Epsilon ‘ e ’ is used for the words “belongs to”, “is an 
element of, etc. 
p e A will be be read as “p belongs to set A” or “p is an element of set A”. 
In the same way ; q e A, r e A, s e a. and t e A. 
The symbol ‘e not’ stands for “does not belong to” also for “is not an element 
of. 
a e not A will be read as “a does not belong to set A” or “a is not an element 
of set A”. 
4. Properties of a set : 
? The change in order of writing the elements does not make any change in 
the set. 
? If one or many elements of a set are repeated, the set remains the same. 
5. Notation (Representation) of a set : 
? Description method : In this method, a well-defined description about the 
elements of the set is made. 
? Roster or Tabular Method : In this method, the elements (members) of a set 
are written inside a pair of curly braces and are separated by commas. 
? Rule or Set Builder Method : In this method, actual elements of the set are 
not listed but a rule or a statement or a formula, in the briefest possible way, 
is written inside a pair of curly braces. 
EXERCISE 10(A) 
Question 1. 
State whether or not the following elements form a set; if not, give reason: 
(i) All easy problems in your text book. 
(ii) All three sided figures. 
(iii) The first five counting numbers. 
(iv) All the tall boys of your class. 
(v) The last three days of the week. 
(vi) All triangles that are difficult to draw. 
(vii) The first three letters of the English alphabet. 
(viii) All tasty fruits. 
(ix) All clever boys of class 6. 
(x) All good schools in Delhi. 
(xi) All the girls in your class, whose heights are less than your height. 
(xii) All the boys in your class, whose heights are more than your height. 
(xiii) All the problems in your Mathematics book, which are difficult for Amit. 
Solution: 
(i) No; some problems may be easy for one person but may be difficult to some other 
person. Objects are not well- defined. 
(ii) Yes. 
(iii) Yes. 
(iv) No; it is not mentioned that the boys must be taller than which boy. If we consider 
three boys A, B and C; boy B can be taller than A but not necessarily taller than C. 
(v) Yes 
(vi) No; it may be difficult for one boy to draw a given triangle but to some other boy it 
may be easy to draw the same triangle. 
(vii) Yes 
(viii) No; a fruit may be tasty for one person and may not be tasty to other person / 
persons. 
(ix) No; clever in what respect and from whom out of six ? 
(x) No; all the people can not find the same schools as good as others said. So, the 
objects are not well-defined. 
(xi) Yes 
(xii) Yes 
(xiii) Yes. 
EXERCISE 10(B) 
Question 1. 
If set A = {2, 3, 4, 5, 6}, state which of the following statements arc true and which are 
false : 
(i) 2 ? A 
(ii) 5, 6 ? A 
(iii) 3, 4, 7 ? A 
(iv) 2, 8 ? A 
Solution: 
(i) True 
(ii) True 
(iii) False 
(iv) False 
Question 2. 
If set B = {4, 6, 8, 10, 12, 14}. State, which of the following statements is correct and 
which is wrong : 
(i) 5 ? B 
(ii) 12 ? B 
(iii) 14 ? B 
(iv) 9 ? B 
(v) B is a set of even numbers between 2 and 16. 
(vi) 4,6 and 10 are die members of the set B. Also, write the wrong statements correctly. 
Solution: 
(i) Wrong ; 5  B 
(ii) Correct 
(iii) Correct 
(iv) Wrong ; 9  B 
(v) Correct 
(vi) Correct. 
Question 3. 
State, whether true or false : 
(i) Sets {4, 9, 6,2} and {6, 2, 4, 9} are not the same. 
(ii) Sets {0, 1, 3, 9, 4} and {4, 0, 1, 3, 9} are the same. 
(iii) Sets {5, 4} and {5, 4, 4, 5} are not the same. 
(iv) Sets {8, 3} and {3, 3, 8} are the same. 
(v) Collection of vowels used in the word ‘ALLAHABAD’ forms a set. 
(vi) If P is the set of letters in the word ‘ROOP’; then P = (p, o, r) 
(vii) If M is the set of letters used in the word ‘MUMBAI’, then: M = {m, u, b, a, i} 
Solution: 
(i) False. 
(ii) True. 
(iii) False. 
(iv) True. 
(v) True. 
(vi) True. 
(vii) True. 
Question 4. 
Write the set containing : 
(i) the first five counting numbers. 
(ii) the three types of angles. 
(iii) the three types of triangles. 
(iv) the members of your family. 
Page 4


IMPORTANT POINTS 
In our day-to-day life we often speak or hear about different types of collections. 
Such as : 
(i) A collection of stamps. 
(ii) A collection of toys : 
(iii) A collection of books, etc. 
In the same way, we have different types of groups made for different activities. 
Such as : 
(i) A group of boys playing hockey. 
(ii) A group of girls playing badminton. 
(iii) A group of students going for picnic, etc. 
In mathematics, a collection of particular things or a group of particular objects is called 
a set. 
1. Definition of a Set : A set is a collection of well-defined objects. 
2. Meaning of “Well-Defined” : Well- defined means, it must be absolutely clear 
that which object belongs to the set and which does not. 
3. Elements (or, members) of a set : The objects used to form a set are called its 
elements or its members. 
Keep in Mind : 
? The pair of curly braces { } denotes a set. 
? The Greek letter Epsilon ‘ e ’ is used for the words “belongs to”, “is an 
element of, etc. 
p e A will be be read as “p belongs to set A” or “p is an element of set A”. 
In the same way ; q e A, r e A, s e a. and t e A. 
The symbol ‘e not’ stands for “does not belong to” also for “is not an element 
of. 
a e not A will be read as “a does not belong to set A” or “a is not an element 
of set A”. 
4. Properties of a set : 
? The change in order of writing the elements does not make any change in 
the set. 
? If one or many elements of a set are repeated, the set remains the same. 
5. Notation (Representation) of a set : 
? Description method : In this method, a well-defined description about the 
elements of the set is made. 
? Roster or Tabular Method : In this method, the elements (members) of a set 
are written inside a pair of curly braces and are separated by commas. 
? Rule or Set Builder Method : In this method, actual elements of the set are 
not listed but a rule or a statement or a formula, in the briefest possible way, 
is written inside a pair of curly braces. 
EXERCISE 10(A) 
Question 1. 
State whether or not the following elements form a set; if not, give reason: 
(i) All easy problems in your text book. 
(ii) All three sided figures. 
(iii) The first five counting numbers. 
(iv) All the tall boys of your class. 
(v) The last three days of the week. 
(vi) All triangles that are difficult to draw. 
(vii) The first three letters of the English alphabet. 
(viii) All tasty fruits. 
(ix) All clever boys of class 6. 
(x) All good schools in Delhi. 
(xi) All the girls in your class, whose heights are less than your height. 
(xii) All the boys in your class, whose heights are more than your height. 
(xiii) All the problems in your Mathematics book, which are difficult for Amit. 
Solution: 
(i) No; some problems may be easy for one person but may be difficult to some other 
person. Objects are not well- defined. 
(ii) Yes. 
(iii) Yes. 
(iv) No; it is not mentioned that the boys must be taller than which boy. If we consider 
three boys A, B and C; boy B can be taller than A but not necessarily taller than C. 
(v) Yes 
(vi) No; it may be difficult for one boy to draw a given triangle but to some other boy it 
may be easy to draw the same triangle. 
(vii) Yes 
(viii) No; a fruit may be tasty for one person and may not be tasty to other person / 
persons. 
(ix) No; clever in what respect and from whom out of six ? 
(x) No; all the people can not find the same schools as good as others said. So, the 
objects are not well-defined. 
(xi) Yes 
(xii) Yes 
(xiii) Yes. 
EXERCISE 10(B) 
Question 1. 
If set A = {2, 3, 4, 5, 6}, state which of the following statements arc true and which are 
false : 
(i) 2 ? A 
(ii) 5, 6 ? A 
(iii) 3, 4, 7 ? A 
(iv) 2, 8 ? A 
Solution: 
(i) True 
(ii) True 
(iii) False 
(iv) False 
Question 2. 
If set B = {4, 6, 8, 10, 12, 14}. State, which of the following statements is correct and 
which is wrong : 
(i) 5 ? B 
(ii) 12 ? B 
(iii) 14 ? B 
(iv) 9 ? B 
(v) B is a set of even numbers between 2 and 16. 
(vi) 4,6 and 10 are die members of the set B. Also, write the wrong statements correctly. 
Solution: 
(i) Wrong ; 5  B 
(ii) Correct 
(iii) Correct 
(iv) Wrong ; 9  B 
(v) Correct 
(vi) Correct. 
Question 3. 
State, whether true or false : 
(i) Sets {4, 9, 6,2} and {6, 2, 4, 9} are not the same. 
(ii) Sets {0, 1, 3, 9, 4} and {4, 0, 1, 3, 9} are the same. 
(iii) Sets {5, 4} and {5, 4, 4, 5} are not the same. 
(iv) Sets {8, 3} and {3, 3, 8} are the same. 
(v) Collection of vowels used in the word ‘ALLAHABAD’ forms a set. 
(vi) If P is the set of letters in the word ‘ROOP’; then P = (p, o, r) 
(vii) If M is the set of letters used in the word ‘MUMBAI’, then: M = {m, u, b, a, i} 
Solution: 
(i) False. 
(ii) True. 
(iii) False. 
(iv) True. 
(v) True. 
(vi) True. 
(vii) True. 
Question 4. 
Write the set containing : 
(i) the first five counting numbers. 
(ii) the three types of angles. 
(iii) the three types of triangles. 
(iv) the members of your family. 
(v) the first six consonants of the English Alphabet. 
(vi) the first four vOWels of the English Alphabet. 
(vii) the names of any three Prime-Ministers of India. 
Solution: 
(i) {1, 2, 3, 4, 5} 
(ii) {acute-angle, obtuse-angle, right-angle}. 
(iii) {scalene triangle, isosceles triangles, equilateral triangle}. 
(iv) { Write the name of family member}. 
(v) {b, c, d, f, g, h} 
(vi) {a, e, i, o} 
(vii) {J.L. Nehru, A.B. Vajpayee, Dr. Manmohan Singh}. 
Question 5. 
(a) Write the members (elements) of each set given below : 
(i) {3, 8, 5, 15, 12, 7} 
(ii) {c, m, n, o, s} 
(b) Write the sets whose elements are : 
(i) 2, 4, 8, 16, 64 and 128 
(ii) 3, 5, 15, 45, 75 and 90 
Solution: 
(a) (i) 3, 8, 5, 15, 12 and 7 
(ii) c, m, n, o and s 
(b) (i) {2, 4, 8, 16, 64, 128} 
(ii) {3, 5, 15, 45, 75, 90} 
Question 6. 
(i) Write the set of letters used in the word ‘BHOPAL’. 
(ii) Write the set of vowels used im the word ‘BENGAL’. 
(iii) Write the set of consonants used in the word ‘HONG KONG’. 
Solution: 
(i) {b, h, o, p, a, 1} 
(ii) {e, a} 
(iii) {h, o, n, g, k} 
EXERCISE 10(C) 
Question 1. 
Write each of the following sets in the Roster Form : 
(i) The set of five numbers each of which is divisible by 3. 
(ii) The set of integers between – 4 and 4. 
(iii) {x: x is a letter in the word ‘ SCHOOL’} 
(iv) {x: x is an odd natural number between 10 and 20} 
(v) {Vowels used in the word ‘AMERICA’} 
(vi) {Consonants used in the * word ‘MADRAS’} 
Solution: 
Page 5


IMPORTANT POINTS 
In our day-to-day life we often speak or hear about different types of collections. 
Such as : 
(i) A collection of stamps. 
(ii) A collection of toys : 
(iii) A collection of books, etc. 
In the same way, we have different types of groups made for different activities. 
Such as : 
(i) A group of boys playing hockey. 
(ii) A group of girls playing badminton. 
(iii) A group of students going for picnic, etc. 
In mathematics, a collection of particular things or a group of particular objects is called 
a set. 
1. Definition of a Set : A set is a collection of well-defined objects. 
2. Meaning of “Well-Defined” : Well- defined means, it must be absolutely clear 
that which object belongs to the set and which does not. 
3. Elements (or, members) of a set : The objects used to form a set are called its 
elements or its members. 
Keep in Mind : 
? The pair of curly braces { } denotes a set. 
? The Greek letter Epsilon ‘ e ’ is used for the words “belongs to”, “is an 
element of, etc. 
p e A will be be read as “p belongs to set A” or “p is an element of set A”. 
In the same way ; q e A, r e A, s e a. and t e A. 
The symbol ‘e not’ stands for “does not belong to” also for “is not an element 
of. 
a e not A will be read as “a does not belong to set A” or “a is not an element 
of set A”. 
4. Properties of a set : 
? The change in order of writing the elements does not make any change in 
the set. 
? If one or many elements of a set are repeated, the set remains the same. 
5. Notation (Representation) of a set : 
? Description method : In this method, a well-defined description about the 
elements of the set is made. 
? Roster or Tabular Method : In this method, the elements (members) of a set 
are written inside a pair of curly braces and are separated by commas. 
? Rule or Set Builder Method : In this method, actual elements of the set are 
not listed but a rule or a statement or a formula, in the briefest possible way, 
is written inside a pair of curly braces. 
EXERCISE 10(A) 
Question 1. 
State whether or not the following elements form a set; if not, give reason: 
(i) All easy problems in your text book. 
(ii) All three sided figures. 
(iii) The first five counting numbers. 
(iv) All the tall boys of your class. 
(v) The last three days of the week. 
(vi) All triangles that are difficult to draw. 
(vii) The first three letters of the English alphabet. 
(viii) All tasty fruits. 
(ix) All clever boys of class 6. 
(x) All good schools in Delhi. 
(xi) All the girls in your class, whose heights are less than your height. 
(xii) All the boys in your class, whose heights are more than your height. 
(xiii) All the problems in your Mathematics book, which are difficult for Amit. 
Solution: 
(i) No; some problems may be easy for one person but may be difficult to some other 
person. Objects are not well- defined. 
(ii) Yes. 
(iii) Yes. 
(iv) No; it is not mentioned that the boys must be taller than which boy. If we consider 
three boys A, B and C; boy B can be taller than A but not necessarily taller than C. 
(v) Yes 
(vi) No; it may be difficult for one boy to draw a given triangle but to some other boy it 
may be easy to draw the same triangle. 
(vii) Yes 
(viii) No; a fruit may be tasty for one person and may not be tasty to other person / 
persons. 
(ix) No; clever in what respect and from whom out of six ? 
(x) No; all the people can not find the same schools as good as others said. So, the 
objects are not well-defined. 
(xi) Yes 
(xii) Yes 
(xiii) Yes. 
EXERCISE 10(B) 
Question 1. 
If set A = {2, 3, 4, 5, 6}, state which of the following statements arc true and which are 
false : 
(i) 2 ? A 
(ii) 5, 6 ? A 
(iii) 3, 4, 7 ? A 
(iv) 2, 8 ? A 
Solution: 
(i) True 
(ii) True 
(iii) False 
(iv) False 
Question 2. 
If set B = {4, 6, 8, 10, 12, 14}. State, which of the following statements is correct and 
which is wrong : 
(i) 5 ? B 
(ii) 12 ? B 
(iii) 14 ? B 
(iv) 9 ? B 
(v) B is a set of even numbers between 2 and 16. 
(vi) 4,6 and 10 are die members of the set B. Also, write the wrong statements correctly. 
Solution: 
(i) Wrong ; 5  B 
(ii) Correct 
(iii) Correct 
(iv) Wrong ; 9  B 
(v) Correct 
(vi) Correct. 
Question 3. 
State, whether true or false : 
(i) Sets {4, 9, 6,2} and {6, 2, 4, 9} are not the same. 
(ii) Sets {0, 1, 3, 9, 4} and {4, 0, 1, 3, 9} are the same. 
(iii) Sets {5, 4} and {5, 4, 4, 5} are not the same. 
(iv) Sets {8, 3} and {3, 3, 8} are the same. 
(v) Collection of vowels used in the word ‘ALLAHABAD’ forms a set. 
(vi) If P is the set of letters in the word ‘ROOP’; then P = (p, o, r) 
(vii) If M is the set of letters used in the word ‘MUMBAI’, then: M = {m, u, b, a, i} 
Solution: 
(i) False. 
(ii) True. 
(iii) False. 
(iv) True. 
(v) True. 
(vi) True. 
(vii) True. 
Question 4. 
Write the set containing : 
(i) the first five counting numbers. 
(ii) the three types of angles. 
(iii) the three types of triangles. 
(iv) the members of your family. 
(v) the first six consonants of the English Alphabet. 
(vi) the first four vOWels of the English Alphabet. 
(vii) the names of any three Prime-Ministers of India. 
Solution: 
(i) {1, 2, 3, 4, 5} 
(ii) {acute-angle, obtuse-angle, right-angle}. 
(iii) {scalene triangle, isosceles triangles, equilateral triangle}. 
(iv) { Write the name of family member}. 
(v) {b, c, d, f, g, h} 
(vi) {a, e, i, o} 
(vii) {J.L. Nehru, A.B. Vajpayee, Dr. Manmohan Singh}. 
Question 5. 
(a) Write the members (elements) of each set given below : 
(i) {3, 8, 5, 15, 12, 7} 
(ii) {c, m, n, o, s} 
(b) Write the sets whose elements are : 
(i) 2, 4, 8, 16, 64 and 128 
(ii) 3, 5, 15, 45, 75 and 90 
Solution: 
(a) (i) 3, 8, 5, 15, 12 and 7 
(ii) c, m, n, o and s 
(b) (i) {2, 4, 8, 16, 64, 128} 
(ii) {3, 5, 15, 45, 75, 90} 
Question 6. 
(i) Write the set of letters used in the word ‘BHOPAL’. 
(ii) Write the set of vowels used im the word ‘BENGAL’. 
(iii) Write the set of consonants used in the word ‘HONG KONG’. 
Solution: 
(i) {b, h, o, p, a, 1} 
(ii) {e, a} 
(iii) {h, o, n, g, k} 
EXERCISE 10(C) 
Question 1. 
Write each of the following sets in the Roster Form : 
(i) The set of five numbers each of which is divisible by 3. 
(ii) The set of integers between – 4 and 4. 
(iii) {x: x is a letter in the word ‘ SCHOOL’} 
(iv) {x: x is an odd natural number between 10 and 20} 
(v) {Vowels used in the word ‘AMERICA’} 
(vi) {Consonants used in the * word ‘MADRAS’} 
Solution: 
(i) {3, 6, 9, 12, 15} 
(ii) {-3, -2, -1, 0, 1, 2, 3} 
(iii) {s, c, h, o, 1} 
(iv) {11, 13, 15, 17, 19} 
(v) (a, e, i) 
(vi) {m, d, r, s} 
Question 2. 
Write each given set in the Roster Form : 
(i) All prime numbers between one and twenty. 
(ii) The squares of first four natural numbers. 
(iii) Even numbers between 1 and 9. 
(iv) First eight letters of the English alphabet. 
(v) The letters of the word ‘BASKET’. 
(vi) Four cities of India whose names start with the letter J. 
(vii) Any four closed geometrical figures. 
(viii) Vowels used in the word ‘MONDAY’. 
(ix) Single digit numbers that are perfect squares as well. 
Solution: 
(i) {2, 3, 5, 7, 11, 13, 17, 19} 
(ii) {12, 22, 32, 42} = {1, 4, 9, 16} 
(iii) {2, 4, 6, 8} 
(iv) {a, b, c, d, e, f, g, h} 
(v) {b, a, s, k, e, t} 
(vi) {Jaipur, Jodhpur, Jalandhar, Jaunpur} 
(vii) {?, O, ?, O} 
(viii) {o, a} 
(ix) {0, 1, 4, 9} 
Question 3. 
Write each given set in the Set- Builder Form : 
(i) {2, 4, 6, 8, 10} 
(ii) {2, 3, 5, 7, 11} 
(iii) {January, June, July} 
(iv) {a, e, i, o, u} 
(v) {Tuesday, Thursday} 
(vi) {1,4,9, 16, 25} 
(vii) {5,10,15,20,25,30} 
Solution: 
(i) {x : x is an even natural number less than 12} 
(ii) {x : x is a prime number less than 12} 
(iii) {x : x is a months of the year whose name starts with letter J} 
(iv) {x : x is a vowel in English alphabets} 
(v) {x : x is a day of the week whose name starts with letter T} 
(vi) {x: x is a perfect square natural number upto 25} 
(vii) {x : x is a natural number upto 30 and divisible by 5}.