Operations and Supply Chain Management- 4 quick math problems (half answered)

Operations and Supply Chain Management, 15th Edition ©2018 | Jacobs, Chase | McGraw-Hill
This is the book used.
Chapter 1: Question 9. Once you complete a, b, and c (show your work) explain what these results tell you overall and what actions would you take.
Chapter 2: Question 17. In addition to the calculation and question asked, explain what additional questions you would need answers to before making any type of decision from the results of your calculation.
Chapter 3: Question 12.
Chapter 4: Question 5.