Sample Space = Set of all possible outcomes Event Space = Set of outcomes we want to happen (selecting a prime number)
Let, S = sample space E = event space
So, S = {1,2,3,4,5,6,7,8,9,10,11,12,13,14,15} E = {2,3,5,7,11,13} note: 1 is not prime
Furthermore, n(S) = number of items in set S n(S) = 15 n(E) = number of items in set E n(E) = 6
Divide the two values to find the probability of selecting a prime P(E) = probability of event E happening (ie, getting a prime) P(E) = n(E)/n(S) P(E) = 6/15 P(E) = 2/5
The answer as a fraction is 2/5 In decimal form, the answer is 0.4 In percent form, the answer is 40%
