Hi Martin and welcome to the Captivate forums!
Unfortunately, quizzes in Captivate aren't very
sophisticated. The scoring mechanism is pretty much all or nothing.
You can tell the user they passed a given quiz with 70%, but
there's no way to group the results into smaller chunks.
Captivate is really meant to report basic scores back to a
Learning Management System, where more advanced reporting
capability is typically found. In a perfect scenario, you would use
Captivate to design a series of smaller quizzes for each continent
with each quiz showing the user their "topic-level" score, then
have the LMS aggregate those results into an overall score... the
70% total in your example. But that's just hypothetical unless you
have an LMS that supports such a thing.
As for a time limit, you can *sort of* limit the time in a
quiz by assigning a maximum time to each question slide. For
example, limiting 50 questions to 1 hour means you'd limit each
question to roughly 1 minute.
It's not very flexible, and the timing option is only
available with the built-in question slides, but that's pretty much
as good as it gets in Captivate.