3.3 The Addition Rule

1
3.3 The Addition Rule

• Important Concepts
• Mutually Exclusive Events
• Using the Addition Rule to Find or
  Probabilities

2
3.3 The Addition Rule

• Card Draw Problem
• Select one card from a deck of 52.
• What is the probability the card is a 5 or is a
  King?
• What is the probability the card is a 10 or a
  red card?
• We can calculate or probabilities using what
  we learned in section 3.1. Sometimes, it is
  easier to use the Addition Rule.

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3.3 The Addition Rule

• If we have an or probability, we need to ask
  ourselves an important question
• Can the events in question occur simultaneously?
• If they cannot occur at the same time, we say the
  events are mutually exclusive. If they can, we
  say they are not mutually exclusive.
• 10 p. 162
• 12 p. 162

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3.3 The Addition Rule

• The Addition Rule
• P( A or B ) P( A ) P( B ) P( A and B )
• If A and B are mutually exclusive events, then
  the Addition Rule becomes
• P( A or B ) P( A ) P( B )
• 18 p. 163 (Die Toss)
• 24 p. 164 (Junk Food Tax)