The graph below shows the velocity (in feet per second) of an experimental car for OS t S 24 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? (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 /sec 626 4} 374 1 94 86 50 t seconds