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tomo

The population of registered voters contains 45% republicans and 55% democrats. If 25% of republicans and 75% of democrats favor an issue, and a person who is chosen at random favors the issue, what is the probability that she was a democrat?

  • one year ago
  • one year ago

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  1. tomo
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    This is what i have come up with so far. P(republican) = .45 P(democrat) = .55 P(republican and favors) = .25*.45 P(democrat and favors) = .75 *.55 P(favor) = P(republican AND favors) + P (democrat AND favors) therefore P(democrat given that favors) = P(democrat and favors)/ (Pfavors)

    • one year ago
  2. blurbendy
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    Hm, well this is what I came up with. Still thinking about it. 45*4 republicans and 55*4 democrats, let If 25% of republicans favor an issue means=45 and 75% of democrats favor an issue means = 165 total who favours = 210 P of her to be democrat= 165/210 .785

    • one year ago
  3. blurbendy
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    No wait

    • one year ago
  4. tomo
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    yeah, I got .786 too. I was confused if the question was asking about P(democrat given that she favors the bill) or something like P(democrat and favors), but we are given that in the problem statement.

    • one year ago
  5. blurbendy
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    I'm pretty sure it's ~.785

    • one year ago
  6. blurbendy
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    Would be nice to get a second opinion though

    • one year ago
  7. kropot72
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    I get P(democrat) = 0.7857

    • one year ago
  8. tomo
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    same here. i just rounded up

    • one year ago
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