Yeah, i did that question before i had a look at the solutions. i got 28.1m as well. They are quite good, as you said its better than nothing, but the forming processes are out of the syllabus.
And here are the 2003/02/01 band 6 ansrwers. http://arc.boardofstudies.nsw.edu.au/go/hsc/std-packs/