Excel treats dates as integer numbers, and times as fractional parts of
a day. For instance, my system time is 12/2/2005 4:04:25 PM Eastern
U.S. Excel's equivalent of this timestamp is 38688.6697337963. Try
this yourself by entering =NOW(), then change that cell's format to a
number with a few decimal places.

So your .46875 may be correct if you multiply it be 24 to convert the
fractional portion of a day into hours: I get 11.25, or 11 hours 15
minutes.

How are your start times and end times entered?