The probability that the total on the two die is 4 or more. (To use the law of total probability, find the probability that the score is 4 or more if the first die gives a 1, if the first die gives a 2, and if the first die gives a 3.)
Somebody invents a three-sided die that gives scores of 1, 2, or 3, each with probability 1/3. Two such die are rolled. Use the law of total probability to find the above probability, and then find them directly by counting.