The areas of cross sections of Lake Nogebow at 5-m intervals are given in the table. Depth (m) 0 5 10 15 20 Area (million m) 2.3 1.6 1.2 0.835 0.227 The following figure shows a contour map of the lake. 20 15 10' 5 Find the left-endpoint and right-endpoint approximations to the integral of cross-sectional area. (Use decimal notation. Give your answers to three decimal places if necessary.) left-endpoint approximation: right-endpoint approximation: Estimate the volume V of the lake by taking the average of the right- and left-endpoint approximations. (Use decimal notation. Give your answer to four decimal places.) V = million m 3 million m3 million m3