Question 252231
There are 6 choices but we need only 3 for a triangle. So we have 6C3 total combinations, which is 20 total choices. Of theses 20, a triangle must satisfy the triangle inequality theorem. The only options that work are: 
3, 5, 7 ; 5, 7, 11 ; 3, 11, 13 ; 5, 11 , 13 ; and 7, 11, 13. There are 5 successful ways out of 20 total ways so, 5/20 = 1/4. This is choice (E).