reading the objectives of the SCEA part 1, i find that EJB 2 and EJB 3 seem to be part of the exam.
I find it strange that both versions are part of the exam, although it does make a bit sense since EJB 2 is still in use in a lot of projects.
How many questions about EJB 2 and how many questions about EJB 3 can we expect in the exam ?
But you should know the benefits EJB3 has over EJB2.x. Plus, an architect does need some basic EJB2 knowledge. I mean, if you've already got a working EJB2 environment, you should know that there's really no need to change it.
Focus on the changes between EJB2 and EJB3, which is pretty much the first chapter of every EJB3 book on the market. But you certainly don't need any deep knowledge of EJB2.
There won't be too many direct questions on EJB 2.x, but you need to know EJB 2.x enough to answer questions like, "How does EJB 3 improve so-and-so aspect when compared to EJB 2.x?" . But you can expect the exam to basically focus on EJB 3.