Fran randomly chooses a positive integers n, 1 <= n <= 100. Find the probability that $n/18$ is reducible.
There are 100 numbers, that is the n(S) the number in the sample space.
Prime actors of 18 are 2,3 . The product of prime factors is 6
there are 50 factors of 2, all of those are reducible
There are 33 factors of 3 , all are reducible
There are 16 factors of 6, these have been counted twice
so number of desirable events is 50+33-16 = 67
Prob = 67/100