An ordinary (air) die is a cube with the numbers 1 through 6 on the sides (represented by painted spots). imagine that such a die is rolled twice in succession
and that the face values of the two rolls are added together. this sum is recorded as the outcome of a single trial of a random experiment.
compute the probability of each of the following events:
event a: the sum is greater than 9.
event b: the sum is divisible by 3.
write your answers as exact fractions