Section 7.1 Principles of Probability

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Section 7.1Principles of Probability
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• Sample Space
• The list of all possible outcomes
• Event
• Any subset of the sample space

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• Probability

Relative Frequency
Probability as a percent
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Example 1A test is given 5 gradesA, B, C, D, F

• Give the sample space for the experiment

b) Identify the event passing
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Example 2

• a) Two dice are rolled. What sum has the
  highest probability of occurring?

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b) What is the probability of that sum?
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Example 3

• Person A,B, and C were playing a game and needed
  to decide who would go first. Person A suggested
  tossing 2 dice. If a 3,6,9, or 12 appeared,
  person A would go first. If a 2,5,8,or 11
  appeared, person B would go first. If a 1,4,7,or
  10 appeared, person C would go first. Is this
  fair?

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Example 4

• If births of boys and girls are assumed equally
  likely, what is the probability that a family
  with four children has all girls?

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• Probability of 1 means
• the event will always happen
• Probability of 0 means
• the event will never happen
• Notation
• P(2tails)

Probability of 2 tails