If you do include 1 and 30 into the list of factors to the number 30, then the list of factors is

{1, 2, 3, 5, 6, 10, 15, 30}, 8 numbers in all.

Then your probability is .



If you do not include  1 and 30 into the list of factors to the number 30, then the list of factors is

{2, 3, 5, 6, 10, 15}, 6 numbers in all.

And then your probability is  = .



Choose what you want.