<PRE><B>Question 429572</B>
A new drug can cause two unwanted side effects: drowsiness and headache. 6% of its users experienced drowsiness, 4% experienced headache, and 2% experienced both. 
If a user experienced headache, what is the probability that he also experienced drowsiness?
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P(d|h) = P(d and h)/P(h) = 0.02/0.04 = 1/2
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What is the percentage of users who experienced neither side effect?
P(h or d) = 0.06+0.04-0.02 = 0.08
Therefore P(neither) = 0.02
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Cheers,
Stan H.
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