A set is a group of an object. It is a collection of things usually numbers. It is also defined as the " well-defined collection of objects". It is related with many objects or things. It is a collection of object which is different in nature from something else of a similar type. The objects in the set are called its elements. Objects can be anything; numbers, people, words etc. A set which does not contain any element is called an empty set.
Examples of sets include:
Usually, Capital letter is used to denote set and the small letter is used to denote an element of sets. For example: set A ={p, q, r, s, t}. The symbol '∈' refers set membership and symbol '∉' refers non-membership. For example:
In set: A = {a, b, c, d, e } and B= {f, g, h, i, j}, a ∈ A and f ∉ A, it means, that the element ′a′ belongs to set A but the element f does not belong to set A.
A set can be identified or membership of set can be point out in several ways. It is also the method to identify the sets and its elements.
Two common ways among them are:
The number of elements in a set is called its cardinal number. For example: if a = {a,b, c, d, e} then, the cardinal number of A is 5 and we write n(A) = 5.
A set having finite numbers of elements is called a finite set. For example: A = {1, 2, 3, 4} is a finite set. An infinite set is a set having infinite numbers of elements. For example: B = {1, 2, 3, 4............} is an infinite set.
Some of the set have only one element, the set having only one element is called Singleton set. For example:
C= {x : x is president of America} is a single set.
A set with no element is called the null set or empty set and is denoted by Φ (phi) or simply{ }. For example, the set of all prime numbers between 3 and 5 is a null set. The cardinal number of the null set is Zero.
The two sets, having, at least, one element common is said to be intersecting sets. For example; {3, 4, 5} and {5, 6, 7} are intersecting sets as number 5 is common to both sets.
The two sets, having no common elements are said to be disjoint sets. For example: {a ,b, c} and {1 ,2, 3, 4} are disjoint sets as they have no common elements.
The two sets having a same number of elements are said to be equivalent sets. For example: if A = {p, q, r} and B = {1, 2, 3} then A and B are equivalent sets as n(A) = n (B).
Two sets are said to be equal if both the sets have same elements.
For example: If C = {2, 3, 4} and D= {2, 3, 4} then C = D.
A set which lies between another set (element of any set lies in another set).
For example;
P ={ 1, 2, 3} and Q = {1, 2, 3, 4, 5}
We say that P is the subset of Q since every element of P is in Q. This is denoted by P ⊂ Q. In this case P ≠ Q. We say that P is a proper subset of Q.
Given: A = {1, 2, 3} and B = {2, 3, 4, 5, 6}, what is the relationship between these sets?
We can say A is not a subset of B since A ∉ B.
The statement "A is not a subset of B" is denoted by A ⊄ B.
It helps to show the relationship between these sets.
Given,
P = {1, 2, 3, 4, 5} and Q = {3, 1, 2, 4, 5}, what is the relationship between P and Q?
Recall that the order in which the elements appear in a set is not important. Looking at the elements of these sets, it is clear that:
P ⊂ Q
Q ⊂ P
∴ P = Q
Thus, for any set, if P ⊂ Q and Q ⊂ P, then P = Q. In this case, we say that P is improper subset of Q and we write P ⊆ Q.
What are the differences between proper and improper sets?
Proper subsets contain some elements but not the elements of the original set. An improper subset contains every element of the original cost.
A un.iversal set is a set which contains all the sets under consideration as its subsets.
A universal set is denoted by U. For example, If A = {6, 7, 8}, B = {1, 2, 3, 5, 7} and C = {4, 6, 8, 10} then the universal set of these sets may be taken as {1, 2, 3, 4, 5, 6, 7, 8, 9, 10}
Note that the given sets, the choice of the universal set is not unique. For example, let A = {2, 4, 6, 7}, B = {3, 5, 7, 9} and C = {0, 4, 8, 12, 16} be the given sets. We can choose any of the following as a universal set:
{x : x ∈ W x ≤ 16}
or, {x : x ∈ W}
or, {x : x is an integer} etc.
Solution:
A-B
= {x:x ∈ B and x ∉ B}
= {2,4,6,8,10} - {4,8,10,12,14}
= {2,6}
Solution:
B-A
= {x: x ∈ A and x ∉ A}
= {4,8,10,12,14} - {2,4,6,8,10}
= {12,14}
Solution:
n(U) = 40, n(A) = 25, n(B) = 10 and n(A∩B) = 5
n(A∪B) = n(A) + n(B) - n(A∩B)= 25 + 10 - 5 = 30
n(\(\overline{A}\)) = n(U) – n(A) = 40 - 25 = 15
n_{o}(A) = n(A) - n(A∩B) = 25 - 5 = 20
n_{o}(B) = n(B) - n(A∩B) = 10 - 5 = 5
Solution:
Solution:
A = {x : 3x = 6} = {2}
A is the set which consists of the single element 2 i.e A = {2}. The number 2 belongs to A, it does not equal to A. There is a basic difference between an element p and the singleton set {p}.
Solution:
A - B
= {a,b,c,d,e} - {c,d,e,f,g}
= {a,b}
Solution:
Given information,
Here,
a)
A = {a,b,c,d,e,f,g}
n(A) =7
b)
B = {b, g, h, i, j, l, m, n, o}
n(B) =9
c)
A?B ={b,g}
n(A?B) =2
d)
AUB = {a,b, c, d, e, f, g, ,h i, j, l, m, n, o}
n(AUB) = 14
e)
n_{0}(A) = n(A) -n(A?B) = 7 - 2 =5
f)
n_{0}(B) =n(B) - n(A?B) = 9 -2 =7.
g)
n_{0}(\(\overline{A}\)) = n(U) - n(A) = 15 - 7 = 8
h)
n_{0}(\(\overline{B}\)) = n(U) - n(B0 = 15 - 9 = 6
Solution:
Given information,
A ={2, 4, 6, 8, 10}, B = {4, 8, 10, 12, 14}
A-B = {2,6}
B-A={12,14}
Now, (A-B) U (B-A) = {2,6} U {12,14}
= {2,6,12,14}
Solution:
Given information,
a) A∪B∪C = {0, 1, 2, 3, 4, 5} ∪ {4, 5, 6, 7, 8} ∪ {2, 3, 4, 8, 9}
= {0, 1, 2, 3, 4, 5, 6, 7, 8} ∪ {2, 3, 4, 8, 9}
= {0, 1, 2, 3, 4, 5, 6, 7, 8, 9}
b) ( \(\overline {A∪B∪C}\)) = U - A∪B∪C
= {0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14} - {0, 1, 2, 3, 4, 5, 6, 7, 8, 9}
= {10, 11, 12, 13, 14}
In a class there are 30 students, 21 students like Maths, 16 students like English, 6 students don't like Maths or English. How many students like both Maths and English?
There are 20 people in a room. Of these,15 are holding newspaper and 8 are wearing glasses.Everyone wears glasses or holds newspapers. How many people are wearing glasses and holding a newspaper?
If U= { a, e, i, o, u }, A = {a, e, i } and B = { i, o, u }. Find (overline{A}).
If U ={1, 2, 3, 4, 5, 6, 7, 8}, A = {2, 4, 6, 8} and E= {1, 3, 6, 8}. Find U-A.
If U = {1, 2, 3, 4, 5, 6, 7, 8, 9}, A = {2, 4, 6, 8}, B = {3, 5, 7, 9} and C = {3,6,9}. Find (AUB)-C.
If A = {2, 4, 6, 8, 10} and B = {4, 8, 10, 12, 14}, then find (A-B) U (B-A).
Let U= {1, 2, ....., 8, 9}, A= {1, 2}, B= {1, 2, 3, 4, 5}. Verify the following:
(overline{AUB}).
If A= {1, 3, 5, 7, 9} and B= {2, 3, 5, 7}, What is A(cap)B?
If X = {a, e, i, o, u} and Y= {a, b, c, d, e}, then what is Y - X?
If n(A) = 35, n(B) = 42, n(A(cap)B) = 17 and n((overline{Acup B})) = 22, then find: n(A(cup)B)?
If n(U)= 40, n(A)=20, n(B)= 17 and n(A(cap)B)=(frac{1}{2})n((overline{Acup B})). What is the value of n(A(cap)B)?
In a class there are:
8 Students who play Volley Ball and Basket Ball.
7 students who do not play Volley Ball and Basket Ball.
13 students play Basket Ball.
19 students play Volley Ball.
How many students are there in the class?
In a class there are 30 students:
21 students like Maths.
16 students like English.
6 students do not like Maths and English.
How many students like both Maths and English?
There are 20 people in a room. Of these, 15 are holding newspaper and 8 are wearing glasses. Everyone wears glasses or holds newspaper. How many people wearing glasses and holding newspaper?
From the survey of 100 college students, it was found that 75 students owned motorcycles, 45 owned cars, and 35 owned cars and motorcycle.
a) How many students owned either a car or a motorcycle?
b) How many students did not own either a car or a motorcycle?
You must login to reply
what is n
Mar 08, 2017
3 Replies
Successfully Posted ...
Please Wait...
Jan 28, 2017
1 Replies
Successfully Posted ...
Please Wait...
agyakari chatra
formula khoi ta sir . malai aaudai aaudaina solti.
Jan 04, 2017
1 Replies
Successfully Posted ...
Please Wait...