Practice Problems For each of the following problems: a) Draw the UML Use Case Diagram. b) Write the story for each use case mentioned in the UML Use Case Diagram from part a. 1. A soccer league wants an online system where anyone can view the schedule of games and view the rankings of the teams. In addition, there needs to be a bulletin board where anyone can post messages to the teams. An administrator is responsible for posting the schedule of games, updating the rankings, and removing inappropriate messages in the bulletin board. 2. A system is designed to sell old books. All users are registered as a seller or a buyer. (Registration occurs outside of this system). A seller can post information about the books they have for sale and remove the books once they are sold. A buyer can search the system and view the seller contact information. (They need to contact the seller outside of this system)