Calculate the number of elements belonging to the sets described below:

n(A)=13
n(A∩B)=8
n(A∪B)=20
Determine n(B)

Question

Calculate the number of elements belonging to the sets described below:

n(A)=13
n(A∩B)=8
n(A∪B)=20
Determine n(B)

turingtest · Answer

oops wrote that wrong

turingtest · Answer

$$n(A\cup B)=n(A)+n(B)-n(A\cap B)$$

anonymous · Answer

well the intersection has 8 so B has at least 8
and at most 20 because the union is 20

anonymous · Answer

Not exactly 100% sure about this

turingtest · Answer

*do not give final answers or you will be banned guys*

anonymous · Answer

|dw:1411670737986:dw|

turingtest · Answer

nice drawing, could you explain how you came up with it? @Yaniv

anonymous · Answer

n(b) = 12 then?

anonymous · Answer

leaving 5 in A only because n(A) = 13

anonymous · Answer

or is b 15?

anonymous · Answer

let me start over. A intersect B = 8. There fore you place 8 in the center. The number of elements in A= 13 so you put 5 in A only as 8 + 5 =13. There are 20 elements that make up the entirety of A and B (A union B) so u just subtract 13 from 20 and u have your remaining 7.

anonymous · Answer

yes b is = to 15