The table shows data from a travel agency, representing the number of guests on a trip (x) and the estimated dollar cost of the trip (y).
X 2 3 4 5 6 7 8 9 10
y 2,300 2,750 3,125 3,625 4,200 4,450 5,125 5,750 6,350 When using the median-fit method with summary points (3, 2,750), (6, 4,200), and (9,5,750), what is the approximate slope of the best-fit model? A.483 B.500 C.517 D.706