<PRE><B>Question 235847</B>
In a college 30% students fail in Physics, 25% fail in Mathematics and 10% students fail in both. One student is chosen at random. What is the probability that
a) He fails in Mathematics if he has failed in Physics
P(m|p) = P(m and p)/P(p) = 0.10/0.30 = 1/3
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b) He fails in Physics if he has failed in Mathematics.
P(p|m) = P(p and m)/P(m) = 0.10/0.25 = 10/25 = 2/5
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c) He fails in Physics or Mathematics.
P(p or m) = P(p) + P(m) - P(p and m)
= 0.30 + 0.25 - 0.10 = 0.45
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Cheers,
Stan H.

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