Download 11.3 Probabilty of Independent Events

Lesson 11.4
Concept: Probability of Two Disjoint Events
Two events are disjoint if they have no outcomes in common.
Guidelines: If two events are disjoint, then the probability
that either event occurs is the sum of the probabilities of
the events.
So…….
P(A) represents the probability of Event A.
P(B) represents the probability of Event B.
P(A or B) = P(A) + P(B)
Represents the probability that Event A or
Event B will occur
A dog is going to have puppies.
The probability that a puppy is brown is 1/4.
The probability that is tan in 1/2.
The probability that it is black is 1/4.
The probability that it is male is 1/2.
Assume that a puppy’s color is independent of its gender. What
is the probability that the first puppy born is brown and male?
P(A and B) = P(A) • P(B)
P(brown and male) = P(brown) • P(male)
1•1=1
4 2
8
The probability that the first
puppy is brown and male is 1/8
You roll four number cubes. What is the probability that you roll
four even numbers
The probability that you roll an even number is
3 or 1
6 2
Rolling an even number is an independent event, so
the probability that you roll four even numbers is
the product of the events probabilities.
1•1•1•1 =1
2
2
2 2
16
The probability that you roll four
even numbers is 1/16.