Precision, with Imprecise Words

This morning, after my course on extreme values, some students did show me a question they got from practicals they were suppose to work on, with undergraduate students : To be more specific, they wanted some feedback about point B. Now, let's make it clear : I have no idea what "precision" and "variation" could mean... But let's try and see if we can get something usefull, that might help to understand the question. In order to illustrate, consider the following regression model, plot(cars...