W/C DFU question

So, I have taken my residential test twice now, and I failed! I have done well on everything but the waste and venting portion. I am beginning to believe there is something I'm just not getting, or maybe there is a sneaky trick to the test. Anyways, I would like to know how many 1.6 gravity tank toilets can be put on a 3" drain, (private/public)... and how many flushometer valve toilets can go on a 3" drain, (private/public).

I believe the answer to both is two on a horizontal and three on a vertical drain.

John

I believe the answer to both is THREE, from table 7-5

Three toilets, of any kind, on a 3" line. A fourth toilet requires that it be increased to 4" FROM that point on. However, if this is per the IPC then the answer could be anything, depending on the cheapest way to install it.

three on a horizontal line and 4 on a stack, according to the UPC

Well I think its 4 and 4.

Haha, no its not. Just amused that every post was a different answer. Pretty sure that 3 on horizontal 3" line is correct, but I have no idea on a vertical/stack. If I remember right, this horizontal setup would require one 2" vent between the first (furthest from stack) and second toilets, but I could be wrong (pros, please correct me if I am). I don't ever deal with situations like that, all my multiple toilet situations are stacked vertically (we city people build up, not out )