Question

An unbiased 4-sided and an unbiased 6-sided dice are rolled. The score on the 6-sided dice is subtracted from the score on the 4-sided dice. Find P(0).

Answer 1

The sum is zero if both dices score 1, 2, 3 or 4 at the same time.

Therefore, the probablity P(0) is given by:

P(0) = p(1|4)*(p(1|6) + p(2|4)*(p(2|6) + p(3|4)*(p(3|6) + p(4|4)*(p(4|6) = (1/4)*(1/6) + (1/4)*(1/6) + (1/4)*(1/6) + (1/4)*(1/6) = 1/6