Posted by Amanda on .
A pair of fair dice is tossed once. Find the probability a sum of 5 or 3 appears.
The two dice are assumed to give random and independent results.
So the outcomes for each die is equally probable.
You can construct a 6x6 table containing all 36 possible outcomes, and pick out those with a sum of 3 or 5. The total number of these favourable outcomes divided by 36 gives the required probability.
You are probably familiar with combinatoric counts of the outcomes totaling 3 or 5. The count divided by 36 also gives the required probability.