B. What is the range of optimality for Activity 2(written as A2 below)? (4 a.-10≤A2≤50. d.30≤A2≤90 c.-4≤A2≤56 coefficient for Activity 1 in the objective function (4分) a. will increase by $77.80 d. will remain the same b. will increase by $23 e. can only be discovered by resolving the problem C. will increase by $30 D. If the right-hand side of Resource A changes to 10, then the objective function value: (4分) a. will decrease by $12.50 d. will remain the same b. will decrease by $125 e. can only be discovered by resolving the roblem C. will decrease by $77.80 E. If the objective function coefficients of Activity 1 and Activity 2 are both increased by $10,then:(4分) a. the optimal solution remains the same d. the shadow prices are b. the optimal solution may or may not remain the same. e. None of the above C. the optimal solution will change 2某项目的各项活动的紧前紧后关系及工期如下表所示。请: 1)绘制该项目的PERT网络图;(7分) 2)在图上计算事项最早时间、事项最迟时间和事项时差。(7分) 3)确定关键路线及工期。(6分) (本题共20分) 紧后活动 活动时间 3 ABCDE C D 5 E E 3某机场专用飞机降落跑道,飞机降落时占用跑道的时间服从负指数分布,平 均每架2分钟,飞机按普阿松流到达机场上空,平均到达间隔时间为2.4分 钟,先到先降落。请回答下列问题 1)此问题属于哪一类排队模型?(5分) 2)飞机在机场上空等待降落的平均时间:(5分)B. What is the range of optimality for Activity 2 (written as A2 below)? （4 分） a. -10  A2  50. d. 30  A2  90. b. -44  A2  16. e. 20  A2  80. c. -4  A2  56. C If the coefficient for Activity 1 in the objective function changes to $40, then the objective function value: （4 分） a. will increase by $77.80. d. will remain the same. b. will increase by $23. e. can only be discovered by resolving the problem. c. will increase by $30. D. If the right-hand side of Resource A changes to 10, then the objective function value: （4 分） a. will decrease by $12.50. d. will remain the same. b. will decrease by $125. e. can only be discovered by resolving the problem. c. will decrease by $77.80. E. If the objective function coefficients of Activity 1 and Activity 2 are both increased by $10, then: （4 分） a. the optimal solution remains the same. d. the shadow prices are valid. b. the optimal solution may or may not remain the same. e.None of the above. c. the optimal solution will change. 2 某项目的各项活动的紧前紧后关系及工期如下表所示。请： 1）绘制该项目的 PERT 网络图；（7 分） 2）在图上计算事项最早时间、事项最迟时间和事项时差。（7 分） 3）确定关键路线及工期。（6 分） （本题共 20 分） 活 动 紧后活动 活动时间 A B C D E C C, D E E -- 3 5 6 2 3 3 某机场专用飞机降落跑道，飞机降落时占用跑道的时间服从负指数分布，平 均每架 2 分钟，飞机按普阿松流到达机场上空，平均到达间隔时间为 2.4 分 钟，先到先降落。请回答下列问题： 1） 此问题属于哪一类排队模型？（5 分） 2） 飞机在机场上空等待降落的平均时间；（5 分）