Models of Experimental
Probability
H. Reardon
06 June 2016
ED 321M Demo Lesson
Do Now
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A table that measures 7 feet by
8 feet is located below an
indoor balcony. Drawn on the
table is a rectangle with sides
2 feet and 3 feet. Elsa drops a
coin from the balcony onto the
table without looking.
What is the probability the
coin will hit the table inside
the rectangle?
The probability of the coin hitting the
𝟔
𝟑
Assume the coin will not fall
table inside the rectangle is = .
𝟓𝟔 𝟐𝟖
The probability of the coin hitting the
off the table.
table inside the rectangle is .107.
There is a 10.7% probability that the coin
will hit the table inside the rectangle.
Experimental Probability
 Guiding question: Do the theoretical
rules of probability actually work?
 Marble bags
 In each bag, there are:
 8 clear green marbles
 10 frosted green marbles
 5 clear blue marbles
 10 frosted blue marbles
 12 amber marbles
 16 clear marbles
 10 black marbles
 9 silver marbles
 20 white marbles
 Calculate the theoretical probability
of drawing each color. Record each
probability on your data sheet.
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20
Now…
 We’ll do an experiment!
 One person will draw marbles from
the bag. Another will record data.
Put the marble back after!
 After 20 draws, stop and calculate
the experimental probability of
drawing each color. Record this on
your data sheet.
PE =
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35
𝒕𝒐𝒕𝒂𝒍 𝒏𝒖𝒎𝒃𝒆𝒓 𝒅𝒓𝒂𝒘𝒏 𝒐𝒇 𝒂 𝒄𝒐𝒍𝒐𝒓
𝒕𝒐𝒕𝒂𝒍 𝒏𝒖𝒎𝒃𝒆𝒓 𝒐𝒇 𝒅𝒓𝒂𝒘𝒔
 Repeat this procedure for 40, 60, 80,
and 100 trials.
 Use your data to answer the
questions that follow.
 If you finish, take a look at the
extension questions at the end.
 Ask if you need help!!
Discussion
What do you notice about the data?
Experimental probability is not always
perfectly equal to theoretical probability for an
event.
 As the total number of draws (trials) increases,
the experimental probability results will get
closer and closer to the theoretical probability
results. This is a form of:
The Law of Large Numbers
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40