Page 458 - Algebra 1

L E S S O N Mutually Exclusive and Inclusive Events 68
Warm Up
1. Vocabulary Events where the outcome of one event does not affect the
(33)
Find the probability for one roll of a number cube.
probability of the other event are called .
2. P(less than 4) (14)
Simplify.
4. _2 + _1 (SB 3) 3 6
3. P(multiple of 3) (14)
5. _3 - _1 (SB 3) 4 3
New Concepts
Probability describes the possibility of an event happening. In some cases, the events cannot happen at the same time. For example, when someone tosses a fair coin, there are two possible outcomes: heads or tails. Both outcomes cannot occur at the same time. Two events that cannot both occur in the same trial or experiment are mutually exclusive events, or disjoint events.
Finding the Probability of Mutually Exclusive Events
Math Reasoning
Write Give an example of mutually exclusive events.
Probability of Mutually Exclusive Events
If A and B are mutually exclusive events, then P(A or B) = P(A) + P(B)
Example
1
What is the probability of rolling eitherasumof 6orasumof
11 using two different number cubes?
SOLUTION
Make a table of possible outcomes. Using two number cubes, it is not possible to roll bothasumof 6andasumof 11 at the same time.
Find the probability of each event and add them.
P(A or B) = P(A) + P(B) P(6 or 11) = P(6) + P(11)
= _5 + _2 36 36
= _7 36
Roll of Cube 2
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Online Connection www.SaxonMathResources.com
The probability of rolling either a sum of 6 or a sum of 11 is _7 . 36
Lesson 68 443
Roll of Cube 1