Set Theory

Venn Diagram

What are the SETS?

U or Є = Universal Set

Ε = Elements or Belongs to

Ɇ = Does not belong to

∩ = Intersection

U = Union

Φ or {} = Empty Set

Examples & Question:

Venn Diagram (1st example)

1  A travel agent surveyed 100 people to find out how many of them had visited the districts of Brunei Muara, Tutong and Belait. It is shown in the Venn Diagram below.

 

From the Venn diagram, find the number of people who had visited

a)      Brunei Muara and Tutong

2+4= 6 people

b)      Tutong but not Belait

2+16= 18 people

c)       Brunei Muara only

38 people

d)      None of the districts

20 people

 

Venn Diagram 2nd example

 

From the diagram above, state what is :-

              n (A n B n C) = 4

              n (A n C) = 6 + 4 = 10

              n (A n B) = 4 + 2 = 6

 Formula & Solution ?

 The formula of using Venn diagram are the 'sets' that i have mention on above. For example in Question 1, it asked what is the total between Brunei Muara & Tutong? so to solve this problem its easy, what is the intersect between these two districts. So the intersect are 2 & 4. Then you have to add together this two value. Once you add then you finally found the answer. Same thing like question no.2, but in example 2 they already give the sets between the 3 letters. So all you need to do just focus what is the intersect between these 3 letters (depend what the question ask you what to find)