I need help with this question:

In a large class, the distribution of scores in Midterms 1 and 2 is approximately bivariate normal. Define the following notation. - For i = 1, 2, M is the class average on Midterm i, and 0'12 is the class variance on Midterm i - The correlation between Midterm 1 and 2 scores in the class is p (a) For approximately what proportion of the students was the Midterm 2 score (in standard units) higher than the Midterm 1 score (in standard units)? (b) For approximately what proportion of the students did the two midterm scores (each in standard units) differ by more than 1