Cobbler is right, it is a JAA question.
Both methods - SOB's & Cobbler's - will give you the right answer.
The mathematical basis for this is based on Integration or Calculus
. The simple way to think of it, is as a mean error, therefore if you apply the error at the half way point, 0.06 degrees, you will always get the right answer even if they change the numbers!
Good luck!