Find the class average from student scores.
A class average is the arithmetic mean of every student's score, but reporting it alone hides the shape of the results. The median is given beside it because a few very low scores drag the mean down without describing the typical student, and a mean well below the median is the signature of a struggling tail. The pass rate answers the question the mean cannot: how many students actually cleared the threshold.
Mean and median
Mean = sum of scores / number of students; median = middle value of the sorted scores
Pass rate
Pass rate = students at or above the passing score / total students x 100
Report both. The mean is what most grading systems use, but when the distribution is skewed by a handful of very low or very high marks the median describes the typical student better.
Leave them out rather than entering zero. A zero for non-submission is a policy decision that dramatically lowers the mean, so it should be deliberate rather than accidental.