Answer:
The scene with Jordan Baker in "The Great Gatsby" serves several purposes.
Firstly, it reinforces the idea that Jordan and Nick are not meant to be together. Jordan is a dishonest person, and Nick is a moralist. Their personalities are not compatible, and Nick recognizes this. Jordan's story about cheating in a golf tournament highlights her lack of ethics, and this serves as a reminder to Nick of why their relationship did not work.
Secondly, the scene with Jordan serves to emphasize Gatsby's obsession with Daisy. Jordan tells Nick about how Gatsby and Daisy had been in love years ago, and how Gatsby had bought his mansion in West Egg just to be close to her. This story shows the lengths to which Gatsby has gone to be near Daisy, and how much he is still consumed by his love for her.
Overall, the scene with Jordan Baker helps to deepen the characterization of several key players in the novel, while also advancing the plot and themes.