when using 3 dice what is the probablity of rolling a multiple of 3 and a multiple of 7

Question

Is the above question possible

Answer 1

A multiple of 3 which is also a multiple of 7 is a multiple of 3×7=21. The minimum score after rolling 3 dice is 3 and the maximum is 18, so a score of 21 is not possible and therefore the probability of rolling a multiple of 3 which is also a multiple of 7 is zero.

There are 6³=216 possible outcomes of rolling 3 dice.

The probability of rolling a multiple of 3 is 72/216=⅓; the probability of rolling a multiple of 7  (7 or 14) is 30/216=5/36. These are independent probabilities, because both cannot occur together.

The probability of rolling either a multiple of 3 or a multiple of 7 = ⅓+5/36=17/36.