This is not correct.
Although that method may be used by other institutions in other circumstances, it is not used by the Board of Studies NSW to moderate raw school assessment marks. The moderating procedure uses a quadratic function and is non-linear.
You can verify that the transformation is non-linear by inspecting the conversion graph at the bottom of
this page. It is a curve rather than a straight line.
The detail of the procedure is explained in the following technical paper, a copy of which is attached to this post:
MacCann, R.G. 1995,
The Moderation of Higher School Certificate Assessments using a Quadratic Polynomial Transformation: a Technical Paper, NSW Board of Studies, Sydney.
We implemented a crude
web app some years ago to allow students to experiment with the moderating procedure by entering different marks, but it seems to have ceased functioning through the various site upgrades. Perhaps someone can recreate it.
Attachments: View attachment 24602