This document discusses probability and how to represent the likelihood of events occurring using percentages, fractions, decimals, and probability scales. It provides examples of assigning probability values to events like the sun rising or the temperature reaching a certain level. The key aspects covered are: 1) Probability involves the chance that an event will occur, ranging from impossible (0) to certain (1) 2) The probability of an event occurring plus the probability of it not occurring must equal 1 3) Probability can be expressed in multiple ways like fractions, decimals, percentages, and on a scale

1. Application of Probability
Probability involves the likelihood of events occurring.
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2. Using a percent:
How would you describe the chances that something is
guaranteed to happen?
How would you describe tne chances that something is
guarenteed to not happen?
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3. The probability of an individual event occurring can be
represented on a probability scale as follows.
* an impossible event has a probability value of 0
* a certain event has a probability value of 1
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4. Example 1
Place the following events on a probability scale.
1. The sun will rise in the east next Sunday.
2. The next baby born in your local hospital will be a boy.
3. Somewhere in Manitoba, the temperature will reach at least 4° C
once next year during the month of January.
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5. A convenient way of expressing the probability of an event occurring
is to use the notation: P(event)
For example,
The probability of flipping a coin and having it land heads can be
expressed as: P(H) = 1 : 2
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6. An event has to either occur or not occur, the probability of an event
occurring plus the probability of an event not occurring is a certainty
and equal to 1.
This relationship can be expressed as:
P(event occurring) + P(event not occurring) = 1
P(event not occurring) = 1 ­ P(event occurring)
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7. Probability can be expressed in the following ways:
* a fraction
* a ratio
* a decimal
* a percent
* in words
* on a probability scale
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8. Example 2
Two coins are tossed.
1. Determine all possible outcomes.
2. Express the probability of both coins landing heads in the following
ways:
* a fraction
* a ratio
* a decimal
* a percent
* in words
* on a probability scale with a scale in decimals
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9. P(HH) = 1 : 4
* a fraction: 1/4
* a ratio: 1 : 4
* a decimal: 0.25
* a percent: 25%
* in words: The probability that the two coins will land heads is 1 out of 4.
* on a scale:
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10. Assignment
page 324
Questions 1 ­7
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