I took that test about 8 years ago.  It was about 100-120 general questions.  Some were math but most of them were basic pipefitting knowledge....take-offs, valve assembly, drawings, etc.  It was a pretty tough test.  The place where I took it said that only about 30 % of the peolple passed and the avg score was like 50 or something.  I was fresh out of the union apprenticeship school so I made an 87.