17/02/05 14:32:51.64 y3KE+Pvf.net
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# Aa,Ba,Ca : 恩赦事象 1/3
# Bd,Cd : 死刑宣告 1/2
# p(Aa|Bd) = p(Bd|Aa)*p(Aa) / p(Bd)
# where p(Bd) = p(Bd|Aa)*P(Aa) + p(Bd|Ba)*p(Ba) + p(Bd|Ca)*p(Ca)
= (1/2) *(1/3) + 0*(1/3) + 1*1/3
= 1/2
# ∴ p(Aa|Bd) = p(Bd|Aa)*p(Aa) / p(Bd)
= ((1/2)*(1/3)) / (1/2) = 1/3