Question

what is the max and min time for problem set ?

Answer 1

Since these are open courses, I don't think there is a min or max time that is expected, especially if you're just beginning. It wouldn't be unreasonable to think that some of these will get progressively a bit more difficult and may take an hour or two to finish.

Answer 2

the problem take more than five hour O.o do that mean i didn't understand the lecture well or that is the time for solving the problem ?

Answer 3

Granted, I'm not doing them continuously, and I'm on the 4th problem set, but each one is taking me several hours to complete, if that helps.