Demand explanation on random, unfair, unserious grading!

The professor of information system in JHU BARM program (X4) failed to give any explanation of grading details after we noticed there is unfairness inside her grading. Someone did obviously the worst and worse than the average level of a college student in the presentation but still got good score the same as others. We suspect she gave grade randomly without memorizing the performance. It shouldn't happen in this program and Johns Hopkins. Someone sent an email response saying that the professor had phd and she cannot be more fair. I don't want to make any joke on this logic because, pHD, cannot guarantee anything, including teaching quality and fair grading. We have worked hard, we performed well, we deserved an explanation and we deserve better!