(2, 3, 5, 7, 11, 13, 17 )
We have 35 possible sets
(2,3,5) (2,3,7) (2,3,11) (2,3,13) (2,3, 17)
(2, 5, 7) (2, 5,11) (2, 5, 13) (2,5, 17)
(2, 7,11) (2, 7, 13) (2, 7, 17)
(2, 11,13) (2,11, 17)
(2,13, 17)
(3, 5, 7) (3, 5,11) (3, 5, 13) (3, 5, 17)
(3, 7, 11) (3, 7, 13) (3, 7, 17)
(3, 11, 13,) (3, 11, 17)
(3, 13, 17)
(5, 7, 11) (5, 7, 13) (5, 7, 17)
(5, 11, 13) (5, 11, 17)
(5, 13, 17)
(7, 11, 13) (7, 11, 17)
(7, 13, 17)
(11,13, 17)
By the Triangle Inequality....Only 9 are possible
So 9 / 35