The data given below represent the raw scores for version A, and the adjusted scores for version B.
The scores are low, because the second problem was badly done. You should be spending several hours each week doing practice problems. Not just the homework, but the practice problems I have been posting on the course webpage. You should then compare their solutions with those in the student solution manual (your own copy, or the copy on reserve in the library). If things aren't clear to you, come to office hours, or the MathLab, or to PASS. Given the results on the quiz, many more people should be using those resources than is the case now. And people need to work more practice problems. It is your responsibility to do the problems, and that is the only way to learn this material. Going to lectures is not enough.