The fine art of bullshitOR,
How to fail an exam...
1. Explain the shape of the graph.I don't know about you but I'd have given him at least half points for gumption.
Its curvy, with a higher bit at the end and a rather aesthetically pleasing slope downwards towards a pretty flat strait bit. The actual graph itself consists of 2 strait lines meeting at the lower left hard corner of the graph and moving away at a 90 angle. Each line has an arrow head on the end.