econ 100A and stat 20

<p>I was going to take stat 20 in this spring, but both of the lectures are full. Should I put myself on the waiting list? or should I look for other classes? (my telebears is tomorrow 10:20am. as of now there are 15 people on the waiting list)
and what about 21? I heard two very different opinions about those two... some say that 21 is much harder than 20, and some say they are exactly same... material wise, what are the differences? </p>

<p>My second question is... for my back up class for stat, I was thinking of econ 100A. (I'm taking econ1 right now) but it says 100A is only for sophomores, juniors, and seniors.... and i'm first year student... can I still take it if there are space?</p>