Geometry
Name: ___________________
Date: ___________ Pd. ______
Probability and Shaded Area
What is the simple probability represented by the following area models? Assume these are
regular polygons that have been divided into equal parts.
1._______
1.
2.
3.
2._______
3._______
4. Draw a square split in equal sections to
represent a probability of .25 .
5.
Draw a decagon split in
equal sections to represent
a probability of
9. 6) Johnny Awesome has decided to throw
darts with his best friend Robby Rocker.
.
7) What is the probability that a bean tossed on
the picture will fall inside the trapezoid?
Robby challenged Johnny to hit the center of
the circular dart board. If the dart board has
a radius of 9 inches, and the radius of the
center section is 2 inches, what is the
probability that Johnny Awesome will hit his
target?
8) To win a carnival game, Keisha must throw a dart and hit one of 25 circles in a dart board that
is 4 feet by 3 feet. The diameter of each circle is 4 inches. Approximately what is the
probability that a randomly thrown dart that hits the board would also hit a circle? 1 foot = 12
inches
9) What is the probability that a dart thrown
at a circular dart board with a diameter of
7cm would land in a sector with a central angle
10) What is the probability that a penny thrown
at a square board would land in the red sector of
a circle with a radius of 2 feet and a central
angle of 122 ?
of 42 ?
7 ft
Name: _______________________
Date: ________________
Period: ____
Notes: Probability and Shaded Area
Have you ever played darts? If so, have you thought about what your chances are of landing the dart
on the bullseye? If so, you were thinking about geometric probability.
At first, geometric probability looks difficult. But, if you keep in mind the formula for basic
probability, you will have no problems.
Formula for Probability
# 𝑜𝑓 𝑓𝑎𝑣𝑜𝑟𝑎𝑏𝑙𝑒 𝑜𝑢𝑡𝑐𝑜𝑚𝑒𝑠
# 𝑜𝑓 𝑡𝑜𝑡𝑎𝑙 𝑜𝑢𝑡𝑐𝑜𝑚𝑒𝑠
Ex. 1 If a circle with a radius of 10cm is placed inside a square with a length of 20 cm, what is the
probability that a dart thrown will land inside of the circle?
Ex. 2 All three circles share the same center. The diameter of the bulls-eye is 4cm. The radius of
the middle circle is 6cm. The radius of the outer circle is 9cm. What is the probability that a dart
thrown at the board will land anywhere inside the middle circle but not the bulls-eye?
What is the probability that a penny tossed will land inside the
parallelogram?