events: For any given event, its
contains all the points that are
There are two rules with complementary events:
Complementary events are always mutually exclusive events.
The probability of complementary events always adds to 1.
determining the probability of an event occurring, given another event has already
EXAMPLE 5: Suppose we pick a tasting at random. What is the probability that our randomly selected
tasting has a “good” quality rating?
IE . Anything else
event of interest
compliment pf A
EXAMPLE 6: Suppose we
that the randomly selected tasting was a high priced beer. Then:
How many tastings are known to be from high priced beers?
Of these high priced beers, how many of them have a good quality rating?
What is the probability that a randomly selected tasting has a good quality rating, knowing that it is a
high priced beer?