Question

I roll 5 dice. What is the probability of having a sum of 26 and that one of the dice is a 1?

Answer 1

The outcome of each of dice can be {1,2,3,4,5,6}
If X_i be the outcome of i^th dice, X₁ + X₂ + X₃ + X₄ + X₅ = 26 but it is also given that one if dice is a 1.

which means, Sum of other four dice = 26-1 = 25. But maximum sum of four dice can be 24.

Hence required probability = 0