Please help me for solving this question of statistics subject as soon as possible and please explain each and every aspect clearly.

10) a) A panel of judge A and B graded seven candidates and independently awarded the following marks: [6] Candidate 2 4 5 6 7 Marks by A 40 34 28 30 44 38 31 Marks by B 32 39 26 30 38 34 28 An eighth candidate was awarded 36 marks by judge A while judge B was not present. If judge B were also present, how many marks would you expect him to be awarded to the eighth candidate assuming that the same degree of relationship exists in their judgments? b) Why do we have, in general, two lines of regression? If we are given two lines of regressions then how do we decide which one is the Y on X or X on Y line of regression? Explain clearly. [6]