Bloody hell, I had a decent response typed out yet explorer died as I hit submit... *shakes fist*
I am not a maths person, yet I took a stats unit (only stat2002) and eventually ended up with a 62 after calculating a probable 46 during the exam itself (something along the lines of 35% in an exam worth 70 or 75% of the course total) after a semester of relatively decent prac and quiz results.
I was going to say that 50% should be fine, as flyin' typed, provided that you meet the other requirements for the course (you are only an item on the factory belt throughout first year, afterall).