I got confused as it said the graph showed T squared, meaning we'd have had to draw from 1.41415. But, the experiment only went up to 10s I think but 5 squared is 25, so it wouldn't have been relevant to the question - plus with the graph so small it would have been inaccurate to draw. so I worked it out from the 2.0 mark at l = 0.49
ah how many marks can you drop per paper and still get an a* ?