10 points best answer. How to figure out my grade?

I am currently taking organic chemistry and it is split up into two classes, lecture and lab. On the syllabus, it says that there are three test and a final in the lecture portion of the class, each test being 100 points. In the lab portion, we have 9 labs each worth 100 points. On the syllabus, it says that the 3 tests are 65% of our grade, the final is 20% , and the lab is 15 % of our grade. This doesn't make any sense to me, how can the lecture portion of the class that has 3 test worth 100 points and the final prob being around 100-150 be 65% , when there are 900 points in lab that is 15% of our grade. And how can 1 final worth 100-150 points be 20% when we have 900 points in lab that is only 15%. Anyone out there that can break this lingo down for me?