根据给定材料，使用关键路径分析法，回答问题，答题使用中文，同时请在完成两个问题后对你如何获得解决本题的知识进行简要阐述。

Durham Police Department investigates a murder thattook place on Ninth Street. A red Dodge pick-up truck was seen fleeing themurder scene around the time 911 call was placed. The following table describesthe activities involved in an investigation.

问题一：Draw the PERT/CRM network for this project.+-* 问题二：Use the expected activity times to determine thecritical path. What are the critical path activities? What is the expected timeto complete the investigation?
谢谢大家。