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Exercise 15

Avg difficulty 3.0

Global warming. A Pew Research poll asked 1,306 Americans “From what you’ve read and heard, is there solid evidence that the average temperature on earth has been getting warmer over the past few decades, or not?”. The table below shows the distribution of responses by party and ideology, where the counts have been replaced with relative frequencies.

Response
Earth is Not Don’t Know
warming warming Refuse Total
Conservative Republican 0.11 0.20 0.02 0.33
Party and Mod/Lib Republican 0.06 0.06 0.01 0.13
Ideology Mod/Cons Democrat 0.25 0.07 0.02 0.34
Liberal Democrat 0.18 0.01 0.01 0.20
Total 0.60 0.34 0.06 1.00
  1. Are believing that the earth is warming and being a liberal Democrat mutually exclusive?

  2. What is the probability that a randomly chosen respondent believes the earth is warming or is a liberal Democrat?

  3. What is the probability that a randomly chosen respondent believes the earth is warming given that he is a liberal Democrat?

  4. What is the probability that a randomly chosen respondent believes the earth is warming given that he is a conservative Republican?

  5. Does it appear that whether or not a respondent believes the earth is warming is independent of their party and ideology? Explain your reasoning.

  6. What is the probability that a randomly chosen respondent is a moderate/liberal Republican given that he does not believe that the earth is warming?

Diez, Barr & Çetinkaya-Rundel, OpenIntro Statistics, Probability, End-of-Chapter Exercises, Exercise 15

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Adapted from OpenIntro Statistics © 2019 David Diez, Mine Çetinkaya-Rundel & Christopher D. Barr. Licensed under CC BY-SA 3.0. Source: OpenIntro Statistics. Imported at revision fee2509.