18. The following precedence network is used for assembling a product. You have been asked to achieve an output of 240 units per eight-hour day. All times in this network are in minutes. Balance the line using the following rule: assign tasks to workstations on the basis of most following tasks (Rule 1). Use greatest positional weight (Rule 2) as a tiebreaker. What is the efficiency (%)? 0.2 0.4 0.2 1.2 b + 0.4 1.0 2.0 d e g O 80 O 76 90 83.33 67.5 O None of the provided options O 22.5