點數和為3的可能情況:(1,2)或(2,1)。
\(P(1,2) = P(X=1)\times P(X=2) = \frac{1}{3} \times \frac{1}{12} = \frac{1}{36}\)
\(P(2,1) = P(X=2)\times P(X=1) = \frac{1}{12} \times \frac{1}{3} = \frac{1}{36}\)
總機率 = \(\frac{1}{36} + \frac{1}{36} = \frac{2}{36} = \frac{1}{18}\)
答案為 \(\frac{1}{18}\)。
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