People is reporting that Stephanie Pratt – the 23-year-old star of The Hills – reached a plea deal with Los Angeles prosecutors in her DUI case Thursday. She was fined, sentenced to three years informal probation and must complete a 12-week alcohol education program, as well as attend Alcoholics Anonymous meetings. DUI charges were dropped in exchange for a no contest plea to one count of misdemeanor “exhibition of speed.” Pratt was arrested Oct. 18 after attending Holly Montag’s birthday party.