Which sentence uses the underlined word correctly? A tried to farther understand the content of…

Which sentence uses the underlined word correctly?
A tried to farther understand the content of the lecture, but the professor skipped around so much that I couldn’t follow my notes.
Becky wanted her parents to extend her curfew farther so she would be able to work more hours during the summer.
The school was farther from Tim’s house than he anticipated, forcing him to have to save more money for gasoline.
The conversation did not go any farther because it was time consuming, and it was preventing progress on the project.