题目
A project is modelled by the activity network shown in Figure 3. The activities are represented by the arcs. The number in brackets on each arc gives the time, in days, to complete the corresponding activity. Each activity requires exactly one worker. The project is to be completed in the shortest possible time.
(a) Complete the precedence table in the answer book to show the immediately preceding activities for the project.
(b) Complete the diagram in the answer book to show the early event times and the late event times.
(c) Calculate a lower bound for the minimum number of workers required to complete the project in the minimum time.
(d) Draw a Gantt (cascade) chart on the grid in the answer book.
(e) Use the Gantt chart to determine the minimum number of workers required to complete the project in the minimum time. You must make specific reference to the number of workers, activities and times.
题目中文翻译
一个项目由图 3 所示的活动网络建模。活动由弧表示。每条弧上括号内的数字是完成对应活动所需的时间（单位：天）。每个活动恰好需要一名工人。项目应在最短时间内完成。
(a) 在答案本中完成紧前活动表，显示项目的紧前活动。
(b) 在答案本中完成图表，显示最早事件时间和最晚事件时间。
(c) 计算在最短时间内完成项目所需最少工人数量的下界。
(d) 在答案本中的网格上绘制甘特图（级联图）。
(e) 使用甘特图确定在最短时间内完成项目所需的最少工人数量。必须具体说明工人数量、活动和时间。