MHB -aux.02 Venn diagram sample space U and events A and B

[karush]

(a) the shaded hopefully shows $(A\cup B)'$

(b) (i) if $(A\cup B)'= 21$ and $n(U)=36$ then $n(A\cup B)=15$
but $n(A)+n(B)=17$ so $n(A\cap B) = 2$

(ii) $P(A\cap B)$ not sure but guessing $2:17$

(c) not sure what "mutually exclusive" means but presume it has to do with the overlap.

never done Venn Diagrams so this is all new ... did look at De Morgan's stuff tho..

 

[MarkFL]

(a) Correct. Anything that is not in either A or B should be shaded, which is what you did.

(b)

(i) Correct.

(ii) I believe you want to use:

$$P(A\cap B)=\frac{n(A\cap B)}{n(U)}$$

(c) Two sets are mutually exclusive if:

$$A\cap B=\emptyset$$

 

[karush]

(a)

(ii) I believe you want to use:

$$P(A\cap B)=\frac{n(A\cap B)}{n(U)}$$

so

$\displaystyle P(A\cap B)=\frac{n(A\cap B)}{n(U)}=

\frac{2}{36}=\frac{1}{16}$

 

[MarkFL]

so

$\displaystyle P(A\cap B)=\frac{n(A\cap B)}{n(U)}=

\frac{2}{36}=\frac{1}{16}$

Not quite...

$$\frac{2}{36}=\frac{2}{2\cdot18}=\frac{1}{18}$$

:D