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Four identical unfair dice are tossed once. Find the probability of events in which the sum of numbers (facing up) is 18. Given the probability of face 6 is $1/2$ and that of each other face is $1/10$.

My attempt

ClearAll[data,prob]
data = DeleteCases[Tuples@Table[Range[1, 6], 4], x__ /; Total@x != 18];
prob = (# /. {p_ /; p != 6 -> 1/10, 6 -> 1/2}) & /@ data;
Times @@@ prob // Total

with output $12/125$.

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2 Answers 2

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pd = EmpiricalDistribution[({1, 1, 1, 1, 1, 5}/10) -> Range[6]];
Probability[Total[Array[x, 4]] == 18, Thread[Array[x, 4] \[Distributed] pd]]
(* result 12/125 *)
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Without filtering:

Total[Times @@@ Map[If[# == 6, 1/2, 1/10] &,
                    Flatten[Permutations /@
                            IntegerPartitions[18, {4}, Range[6]], 1], {2}]]
   12/125
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