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Problem of the Week

Problem B

Honesty - the Best Policy?

A reporter is doing interviews at a convention attended by 500 people.

  1. Suppose that she interviews a person at random.

    1. As a fraction, what is the probability that the person always lies?

    2. As a fraction, what is the probability that the person always tells the truth?

  2. Suppose she interviews Joe Public, a person at the convention. The last time she interviewed him, he only told her the truth, so she knows he must be a person who always tells the truth or a person who sometimes tells the truth and sometimes lies. What is the probability that Joe Public always tells the truth?


Strand: Data Management and Probability