Grinstead-Snell-Probability · Problem 4.1.8

Conditional Probability

Mathematics · independence-counterexample

Problem

Let Ω={a,b,c,d,e,f}\Omega = \{a, b, c, d, e, f\}. Assume that m(a)=m(b)=1/8m(a) = m(b) = 1/8 and m(c)=m(d)=m(e)=m(f)=3/16m(c) = m(d) = m(e) = m(f) = 3/16. Let AA, BB, and CC be the events A={d,e,a}A = \{d, e, a\}, B={c,e,a}B = \{c, e, a\}, C={c,d,a}C = \{c, d, a\}. Show that P(A∩B∩C)=P(A)P(B)P(C)P(A \cap B \cap C) = P(A)P(B)P(C) but no two of these events are independent.

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