Intersection of Sets 

 
4.1  Intersection of Sets 
 
Determine and describe the intersection of sets using various representation.
 
  • Intersection of sets exist when there are more than one set.
  • The intersection of set \(P\) and \(Q\) is written using the symbol \(\cap\)
  • Example: Set \(P \cap Q\) contains the common elements of both sets   \(P\) and \(Q\) .
 
  Example   
     
 
  • The intersection of a set \(R\), a set \(S\) and a set \( T\), represented as \(R ∩ S ∩ T\), is a set whose elements consist of all common elements of a set \(R\), a set \(S\) and a set \( T\).
 
     
 
  • The intersection of set can be represented by using Venn Diagrams
 
     
   
 
  Example 2  
     
 

A total of \(140\) Form \(4\) pupils are given the opportunity to attend the intensive classes for Mandarin an Bahasa Melayu subjects.

\(65\) pupils choose Bahasa Melayu, \(70\) pupils choose Mandarin while \(50\) pupils choose both. 

Calculate the total number of pupild who attend the intensive classes. 

 
     
 

Solution:

Steps:

  1. Fill in \(n(B\cap M)= 50\)
  2. Fill in the number of pupils who attend Bahasa Melayu class only \((65-50=15)\)
  3. Fill in the number of pupils who attend Mandarin class only \((70-50=20)\)
  4. Thus, people who attend intensive class \((15+50+20= 85)\)