Chapter 11 Probability Worksheet Page 3
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PROBABILITY (Chapter 11)
OPENING PROBLEM
When Karla dropped some metal nuts she noticed
that they finished either on their ends or on their
sides.
She was interested to know what the
probability was that a nut would finish on its end.
So, she tossed a nut 200 times, and found that it
side
end
finished on its end 137 times.
Later Sam repeated the experiment and the nut finished on its end 145 times.
For you to consider:
² What would Karla’s best estimate be of the chance that the nut will finish on its end?
² What would Sam’s estimate be?
² How can we obtain a better estimate of the chance of an end occurring?
² Hilda said that the best estimate would be obtained when the nut is tossed thousands
of times. Is she correct?
A
EXPERIMENTAL PROBABILITY
We should use suitable language to help us describe what we are doing and the results we
expect and get.
² The number of trials is the total number of times the experiment is repeated.
² The outcomes are the different results possible for one trial of the experiment.
² The frequency of a particular outcome is the number of times that this outcome is
observed.
² The relative frequency of an outcome is the frequency of that outcome divided by the
total number of trials.
For example, when tossing a tin can in the air 250
times, it comes to rest on an end 37 times. We say:
² the number of trials is 250
² the outcomes are ends and sides
² the frequency of ends is 37 and sides is 213
37
² the relative frequency of ends =
¼ 0:148
250
213
² the relative frequency of sides =
¼ 0:852.
250
EXPERIMENTAL PROBABILITY
Sometimes the only way of finding the probability of a particular event occurring is by
experimentation.
Tossing a tin can is one such example. The probability of a can of this shape finishing on its
end is the relative frequency found by experimentation.
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