# MDM4U Skills Tracking; Mutual Exclusivity 2016-03-22

I handed this out yesterday to help you monitor your learning in this part of the course:

Skills Tracking – Probability – booklet

Today we learned about Mutually Exclusive (ME) and Non-Mutually Exclusive (NME) events. ME events can’t happen simultaneously; NME events can.

For example, suppose you’re drawing a card from a shuffled deck. Let $A$ be the event that you draw an ace, let $B$ be the event that you draw a face card, and let $C$ be the event that you draw a heart.

$A$ and $B$ are mutually exclusive – there are no aces that are face cards (and vice versa). But $A$ and $C$ are non-mutually exclusive, since drawing the Ace of Hearts would satisfy both events. Similarly, $B$ and $C$ are NME.

For probability, we can use the following relationship which we learned in set theory:

$P(A \text{ or } B) = P(A) + P(B) - P(A \text{ and } B)$

You have the following questions for practice: Page 340 #2-5, 7.