10.6 Geometric
Probability
Alphabet Soup
Mackenzie Mitchell – Elizabeth Mullins – Jacob Woodford
Vocabulary & Objectives
VOCAB
Geometric probability: a method of calculating probability
based on a geometric measure such as length, angle
measures or area
Used when an experiment has an infinite number of outcomes
-----------------------------------------------------------------------------OBJECTIVES
Calculate geometric probabilities
Use geometric probabilities to predict results in real- world
situations
Example #1- length related
 What is the probability that a random point on AB falls
within one unit of point C?
AB = 12 units
A
B
C
AC = 2 units
 If the point falls between 1 unit to the right of C or 1 unit
to the left of point C, that would be a suitable answer.
Example #1- length related
 Our probability would be:
 1 (  ) + 1 (  ) = 2 units
 Now divide this by the total possible places of selection
(12)
 2/12 = 1/6
 There is one in six chance of having a random point fall
within one unit of point C
Example #2- Angle Related: A
If the red section is 80°, divide 80 by 360 (total number of °s) to find
the probability of landing on that particular section.
Example #2: B
 To find the probability of landing on multiple sections, add up
the angle measures of those sections and divide by 360.
Example #2: C
To find the probability of not landing on one section, subtract
that angle measure (example: yellow, 100°) from 360. Now take
your new number (260) and divide it by 360 to find your
probability.
**Another way to do this is to add up the angle measures of every
section except the specific one (example: yellow) and divide by
360.
Example #3- Using Area: A
1.
Find the area of the shape (in this case:
triangle)
1.
Find the area of the rectangle
1.
Divide the shape’s area by the rectangle’s
area to find the probability
1.
Ta- da!
Example #3: B
1.
Find the area of the shape (in this case:
trapezoid)
1.
Find the area of the rectangle
1.
Divide the shape’s area by the rectangle’s
area to find the probability
1.
Ta- da! Hello Einstein.
Example #3: C
What is the probability that a random point in the blue
rectangle will land in one of the three shapes?
1.
Find the area of the shape (in this case:
circle)
1.
Find the area of the rectangle
1.
Divide the shape’s area by the rectangle’s
area to find the probability
1.
Ta- da! You are a genius.
Thanks for watching!