Assume that the differences are normally distributed. Complete parts (a) through (d) below. Observation 1 2 3 4 5 6 7 8 Xi 53.5 47.8 47.8 50.8 53.3 45.2 43.8 50.6 Yi 54.8 48.9 51.3 54.6 53.4 47.9 47.9 52.8 . . . . . (a) Determine dj = Xi - Y for each pair of data. Observation 5 6 7 8 di (Type integers or decimals.) (b) Compute d and Sa. d= (Round to three decimal places as needed.) Sa = (Round to three decimal places as needed.) (c) Test if Hd 0 H 1 : Hd >0 H1 : Hd