(4) (See Kendall rank correlation coefficient) Suppose that six people, a, b, c, d, e and f, entered their paintings in an exhibition, and judges X and Y scored the paintings within the range a b C d e f of 0 to 50 points and 0 to 100 points, respectively: X 50 45 25 30 35 10 Y 96 75 88 54 29 42 In this case calculate the Kendall rank correlation coefficient rx, and then express it as an irreducible fraction. (9 points)