It is just taking the average of the guidance of between $1,550 and $1,400 which gives $1,475 but I think it will be lower as the grade increases and therefore I round it down to $1,450. This June qtr projection is just a guesswork since it is based parameters that are very fluid. Nothing is concrete or nail down for the June qtr..
So take the forecast with a grain of salt and as I highlighted, use the figures especially the forecast figures at your own risk.
The past qtrs figures are based on what I had extracted from the reports even that I hold no responsibility if I am wrong!!!