1. 18.1 Geometric Probability

2. Remember that in probability, the set of
all possible outcomes of an experiment
is called the sample space. Any set of
outcomes is called an event.
If every outcome in the sample space is
equally likely, the theoretical probability
of an event is

3. Geometric probability is used when an experiment has an infinite number of outcomes. In geometric probability, the probability of an event is based on a ratio of geometric measures such as length or area. The outcomes of an
experiment may be points on a segment or in a plane figure.

5. If an event has a probability p of occurring, the probability of the event not occurring is 1 – p.
Remember!

6. Example 1A: Using Length to Find Geometric Probability
A point is chosen randomly on PS. Find the probability of each event.
The point is on RS.

7. Example 1C: Using Length to Find Geometric Probability
The point is on PQ or QR.
P(PQ or QR) = P(PQ) + P(QR)

8. Example 3B: Using Angle Measures to Find Geometric Probability
Use the spinner to find the probability of each event.
the pointer landing on blue or red
The angle measure in the blue region is 52°.
The angle measure in the red region is 60°.

9. Example 3C: Using Angle Measures to Find Geometric Probability
Use the spinner to find the probability of each event.
the pointer not landing on green
The angle measure in the green region is 108°.
Subtract this angle measure from 360°.

10. Example 4: Using Area to find Geometric Probability
Find the probability that a point chosen randomly inside the rectangle is in each shape. Round to the nearest hundredth.
circle
trapezoid
1 of 2
squares
leftover

11. Assignment
Pg (2-26)
Omit 6, 7, 20, 21, 22