The graph below shows the velocity (in feet per second) of an experimental car for Os t s 20 seconds along with the rectangles used to estimate the distance traveled. (a) Do the rectangles represent a left- or right-hand sum? ---Select--- (b) Do the rectangles lead to an overestimate or an underestimate of the actual distance traveled? ---Select-- V (c) Determine the value of At. At = (d) Determine the estimated distance traveled for the rectangles displayed below. Estimated distance traveled is Units ---Select--- velocity ft/sec 440 265 140 65 40 t seconds 15