Question
Why does the variance formula for a random variable weight squared deviations by probabilities?
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Answer
It measures probability-weighted dispersion around E(X).
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Question
What is the total probability rule used for in a probability tree?
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Answer
To get an unconditional probability by summing relevant joint-path probabilities.
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Question
In a probability tree, how do you find the probability of a full path of sequential events?
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Answer
Multiply the branch probabilities along that path.
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Question
What is the first step in a Bayes problem when you are asked to find P(A∣B)?
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Answer
Identify the prior P(A) and likelihood P(B∣A).
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