It's hard to say, since obviously very very few take both. There do seem to be two theories:
1) The Life science series are dumbed down versions of the Physical science series.
2) The Life science series teach different topics (not necessarily easier) than the Physical science series and the curves are much harsher because of crazy pre-meds.
Either way, plenty of people take the 20 series and the 30 series (and the 1 series) together, so it's definitely possible. The amount of work depends on you.
No, I am being serious. Perhaps in the last few weeks, the professor might have focused on one of the most intense and important chapters by devoting two or three weeks to teaching the materials. But for the most part, my professor literally covered one chapter every week.
I took the class like in 1997, and I got A- in the class! Hehe
Check out the syllabus for Fall 2009, whose schedule is in line with what Arklogic mentioned previously.
According to my old memory, I remember that I had to cover three or four chapters for the first midterm. Perhaps it is not the number of chapters I remember correctly. Maybe it was the number of pages we covered per week. It was something like 30-40 pages every week.
I remember getting shafted for the first midterm by getting like C+. I got the second highest grade in the second midterm, and I did fairly well for the final exam.
Now looking at the syllabus, I must confess that I dont even remember studying for the term "lagrange multipliers".
I should have gone a bit more for my pursuit of quant classes. I could also done pretty well for 33A, the matrix series.
From what I can tell from the Math department website, there seemed to be a big reorganization some time in the late 90's. Or maybe it's just that there's a lot of course information that hasn't been updated since 1997.
The third calculus sequence is Math 31A followed by Math 31E, which is tailored to the needs of the students in economics. This brief course sequence moves more rapidly into multivariable calculus and optimization techniques, at the expense of some of the more technical single-variable calculus material required by physical scientists and engineers.
Associated with the multivariable calculus courses 32A and 32B respectively are two one-unit computer laboratory courses Math 32AL and Math 32BL.
Haha, I remember the exact exam grades I received for that class. Actually, for that matter, I remember exactly what kind of grades I received for every single exame I took during my entire undergraduate study!
In Math 32A, the first midterm really put me down. I really questioned whether I was actually an Asian, LOL. Looking at C+ written on the top of the exam book, I vowed that I would bring that grade for the sake of the family reputation of my hardworking Korean parents. : )