We will use either L6 or R6 for the upper and lower estimates.Since the runner's speed is an increasing function, then L6 will give the lower estimate, and R6 will give the upper estimate.The sub-interval widths ?t for this situation are ?t = 0.5The first two sub-intervals in the table are[0, 0.5]and[0.5, 1.0].When calculating L6, we should use the function valuesv = andv = for these two sub-intervals, respectively.