13.6 The graph of the revenue function R(x) from selling r items is shown below: Revene is in dollars. Revenue 3200TTE 2800 2400 2000 1600 1200H 800 400 0 10 20 30 40 50 60 70 80 90 100 (a) What is the revenue from selling 60 items? (b) What is the marginal revenue (with units) at a sales level of 60 items? (c) Use the marginal revenue to estimate the revenue from selling 70 items instead of 60 items and mark the point of the graph corresponding to this estimate. (d) Mark the point of the graph corresponding to the (exact) revenue from selling 70 items. MATH 103L WoRKBOOK v11@CSUN 51