Probabilities Lesson

Probabilities Notes

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Probabilities

• Probability of an event = (# of ways it can happen) / (total number of outcomes)

  
  

  
  

• The probability of an event can only be between 0 and 1 and can also be written as a percentage.

Key Facts

• Mutually Exclusive: A statistical term describing two or more events that cannot happen simultaneously

• Independent Event:  Those events whose occurrence is not dependent on any other event

Essential Question

• How does describing events as mutually exclusive or independent affect how you find probabilities?

Mutually Exclusive

• Name 1 mutually exclusive event.

Vocab

• Favorable Outcome: is an outcome that is being tested or observed and not necessarily a desirable result. A “favorable” outcome may be a loss for the home team or testing positive for a disease.

• Complement of an event: is the set of all

  outcomes in a sample space that are not

  included in the event.

  
  

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Fill in the Blank

A box contains 100 balls. Thirty of the balls are purple and 10 are orange. If you select one of the balls at random, what is the probability of each of the following events?

a. The ball is purple or orange.

Fill in the Blank

2. A box contains 100 balls. Thirty of the balls are purple and 10 are orange. If you select one of the balls at random, what is the probability of each of the following events?

b. The ball is not purple and not orange.

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