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#### karush

##### Well-known member

- Jan 31, 2012

- 3,241

this is an image of the problem as given, mostly to avoid typo's, but (b) seems to contain a notation that I don't recognize.

well for \(\displaystyle (a)\) find \(\displaystyle p(A\cap B)\)

from the counting Formula:

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

replacing $n$ for $p$ and isolating \(\displaystyle p(A\cap B)\)

\(\displaystyle p(A\cup B)-p(A)-p(B)=p(A\cap B)\)

so..

$1-0.6-0.8=-0.4=p(A\cap B)$

(b) ????