A project manager decomposes the work of the system integration project he is responsible for and estimates the cost of each work unit to obtain its planned cost. At the end of the fourth month, the planned cost, actual cost, and percentage completion of each task are as follows : Task Name Planned Cost Actual Cost percentage completion A 100000 90000 80% B 70000 65000 100% C 80000 75000 90% D 90000 85000 90% E 50000 50000 100% F 20000 20000 90% Question 1: Please calculate the PV, EV, and AC values of the project at the end of the fourth month, and write down the calculation process. Please evaluate the implementation performance of this project in terms of schedule and cost, and explain