Lesson 7.4B
M.3.G.1 Calculate probabilities arising in geometric contexts (Ex. Find the probability
of hitting a particular ring on a dartboard.)
M.3.G.2 Apply, using appropriate units, appropriate formulas (area, perimeter,
surface area, volume) to solve application problems involving polygons, prisms,
pyramids, cones, cylinders, spheres as well as composite figures, expressing
solutions in both exact and approximate forms
M.3.G.3 Relate changes in the measurement of one attribute of an object to changes
in other attributes (Ex. How does changing the radius or height of a cylinder affect its
surface area or volume?)
R.4.G.5 Investigate and use the properties of angles (central and inscribed) arcs,
chords, tangents, and secants to solve problems involving circles
Probability Review

Probability:
The chance that a desired outcome
will occur out of all possible outcomes
Probability Review

A probability will always be a decimal
between 0 and 1

We express a probability as a percent
Non-Geometric Example

Josh has 6 red skittles, 4 purple skittles,
3 green skittles, and 9 yellow skittles in
a bag. If he draws one skittle at
random, what is the probability that he
will draw a green skittle?
Geometric Probability

Geometric probability:
Given a figure, the probability that a
randomly chosen point would lie in the
preferred region
Example
A dart is thrown at random at this dart
board. If the dart hits the board, find the
probability to the nearest percent that it
will land in the shaded region.
Note: on some problems the
probability can just be
reasoned!
4
6
More Examples
A dart is thrown at random at this dart
board. If the dart hits the board, find the
probability to the nearest percent that it
will land in the shaded region.
Example
A dart is thrown at random at this dart board. If the dart
hits the board, find the probability to the nearest
percent that it will land in the shaded region.
What do you notice about this?
If dimensions aren’t given,
CHOOSE YOUR OWN
A good number to use is,
An Even Number
Example
A dart is thrown at random at this dart board. If the dart
hits the board, find the probability to the nearest
percent that it will land in the shaded region.
This is a square with semi-circles.
Now You Try…
A dart is thrown at random at this dart board. If the dart
hits the board, find the probability to the nearest
percent that it will land in the shaded region.
12’
6’