Every specialty will have a slightly different day in the life of a resident. The interviewers want to see that you have done your homework and understand your daily life as a preventive medicine resident. Some programs describe what a resident's day looks like on their website. If the program you applied to does not have that information, speak with former or current fellows and residents or visit the university or medical center and talk to the program directors. It would be best if you understood what your day entails before starting the program, so there are no surprises.