Borisoff recently commented in another thread, "people usually work from 9 to 17".
I'm curious. What are typical work hours in your company or geographic area? 9-17 or 9-5 is a seven hour work day, assuming one hour for lunch. In western Florida, a minimum office day is 8 hours plus one hour for lunch. However in the last few years many people find themselves working through most of their lunch hours and working another half hour on each end of the day making a typical day 9-10 hours. And yes, we work 5 of them. At my company we've had flex time for quite a while, which means you can start earlier or stay later, but are still expected to be available for meetings from 9-4. (So your official schedule can be 7-4, 7:15-4:15, 7:30- 4:30, 8-5, 8:30 - 5:30, 9-6, etc.) You are expected to maintain a consistent schedule and not change schedules from day to day with the concurrence of your manager.
So my answer would be 8-5 or 8-17 with exceptions. What are your hours?