This could be an open-ended question. What I have attempted so far is to assume that the marks are normally distributed with mean = 60, standard deviation = 10. I can somewhat derive the possibility of getting X>80 (HD), X> 70 (D), etc.

Or in the second part, it mentions conditional probability, which leads me into think the application covariance. The probability of study hours and the probability of getting the desired marks. I am not sure those are valid assumptions and would love a second opinion.

This is the complete question.

Please estimate the mark that you will receive for assignment 2. Please provide both a point estimate and an interval estimate (a confidence interval). You don't need to provide a mathematical model, but please explain how do you use conditional information to reach the estimates. Based on the conditional information, explain what you would have done differently to improve that mark?