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Conditional Probability-Multiplication Rule

rndragster

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Jan 25, 2011
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4
Need help completing my homework assignment!


In a battleground state, 60% of all voters are Republicans. Assuming that there are only two parties - Democrat and Republican, if two voters are randomly selected for a telephone survey, what is the probability that they one is a Republican followed by a Democrat? Round your answer to 4 decimal places.

A = 0.6
P(R) * P(D)

0.6 * 1/2 = 0.03

Not sure I am doing it right and not sure how to show the work properly???

Thanks!
 

tkhunny

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Apr 12, 2005
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9,706
Why did you assume there were only two parties?

P(R) + P(D) = 1
 

rndragster

New member
Joined
Jan 25, 2011
Messages
4
Because the question states, "Assuming there are two parties"
 

tkhunny

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You did not answer my question. I did not ask, and I never will, are you a robot and able to comply with the demands of the problem statement?

With this background information: In the problem statement is the assumption that there are only two parties.
I did ask: Is this information necessary? Why is it in there? Does it help solve the problem or is it extraneous?

In any case, I already answered the question.

With only two parties, R & D, P(R) + P(D) = 1. Since we know P(R) = 0.60, what does that make P(D)?
Without the assumption of only two parties, we have P(R) + P(D) + P(something else) = 1 and we can't much solve the problem.
 
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