Personal Tasks Planned, Actual and Duration

We noticed that when creating a personal task in form (11.5.10.2) that there is a difference in the calculation for the Planned, Actual and Duration fields. If we create a task that starts on Monday at 0800 and ends of Friday at 1700 we would like all three fields to show 40 hours. If we enter the start date as 06-MAY-2013 08:00:00 and the end date as 10-MAY-2013 17:00:00 into the Planned, Scheduled and Actual fields then save the task what we see is Planned Effort and Duration  = 105 hours but Actual Effort = 40 hours.

Is there a way we can show the Planned and Duration under Effort as work hours (i.e. 40 hours)?