An experiment is given together with an event Find the model

An experiment is given together with an event. Find the (modeled) probability of each event, assuming that the dice are distinguishable and fair, and that what is observed are the numbers uppermost. (Compare with Exercises 1-10 in Section 7.1.) Two dice are rolled; both numbers are prime. (A positive integer is prime if it is neither 1 nor a product of smaller integers.)

Solution

total sample spaces = 6 * 6 = 36

prime numbers on a die = {2, 3, 5}

sample space for both numbers on dice is prime = 3 * 3 = 9

So, the probability that both numbers on dice is prime = 9 / 36

                                                                                        = 0.25 (ans)