Bill's math class

[Dan_Eastwood]

For reference:

Multiplying Probabilities

Continuing the discussion from Comments on Gpuccio: Functional Information Methodology: Pardon me, but my pet peeve has been perked! @AllenWitmerMiller, bring me my soapbox! I am quoting @Gpuccio here, but only because this is the latest example of an error I see regularly, and darnit, I’m getting tired of correcting some basic probability calculations. The error is, probabilities do not multiply this way. If X is some event and the probability of X occurring in a single trial is 0.1, then the probability of X occurring in two trials generates the following probability distribution: The probability X does not occur in either of two trials: (1.0-0.1)\times(1.0 - 0.1) = 0.9 \times 0.9 = 0.81 The probability X occurs in the first trial but not the second: (0.1)\times(1.0 - 0.1) = 0.1 \times 0.9 = 0.09 The probability X does not occur in the first trial but does in the second: (1.0-0.1)\times(0.1) = 0.9 \times 0.1 = 0.09 The probability X occurs in both the first…