问题
解答题
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答案
=0.1×0.3×0.9+0.2×0.6×1.8+0.3×0.9×2.7 0.1×0.2×0.4+0.2×0.4×0.8+0.3×0.6×1.2
，0.1×0.3×0.9×13+0.1×0.3×0.9×23+0.1×0.3×0.9×33 0.1×0.2×0.4×13+0.1×0.2×0.4×23+0.1×0.2×0.4×33
=
，0.1×0.3×0.9×(13+23+33) 0.1×0.2×0.4×(13+23+33)
=3
．3 8