Student Notes    
 

CONCEPT 1 – Compound Probabilities and Conditional Probability


As mentioned in an earlier objective when we do more than one event in succession (a compound probability) we have to concern ourselves with whether these events are independent or not.


We now have two multiplication rules for these two cases:

 

INDEPENDENT                         P(A and B) = P(A) • P(B)

 

NOT INDEPENDENT                P(A and B) = P(A) • P(B|A)


                                                       P(A and B) = P(B) • P(A|B)


 

When events are independent then P(A and B) = P(A) • P(B).

 

Let us look at some more examples of when the two events are dependent.

 

 

When events are not independent then P(A and B) = P(A) • P(B|A)

 

CONCEPT 2 – Formula connectivity

 

When we learned conditional probability we determined that: