The following table shows the marks (x) obtained in a Christmas examination and the marks (y) obtained in the following summer examination by a group of nine students.

Student Christmas (x) Summer (y) A 57 66 B 3.5 51 C 56 63 D 57 34 66 47. 79 70 81 84 H 84 84 52 53 It is given that Ex=567, y=552, Xxy =36 261, Ex-37 777, Ey-36 112.

(a) Find the equation of the estimated least squares regression line of Y on X.

(b) A tenth student obtained a mark of 70 in the Christmas examination but was absent from the summer examination. Estimate the mark that this student would have obtained in the summer examination. (C)