Possible Duplicate:
“Less” vs. “fewer”
I am quite pedantic when using 'less' versus 'fewer' but don't really understand how the situation works when it comes to temporal phrases. For example 'you must complete the task in less than thirty minutes'. Minutes are countable so on that basis it should be fewer but they are also dividable, you might complete it in twenty and a half minutes so 'less' seems more suitable and sounds better to my ear.
Any thoughts on which is 'correct'?
I have searched the archive but can't find this specific question. If you are going to close the question as a duplicate please give me a pointer to the original version and let me know how you found it.