An Awful MyMaths Homework Question

When I was teaching mean from a frequency table I remember looking on MyMaths and seeing the questions they had (I don’t use MyMaths that much to be honest), and they had this….

Not holding back now…. I think this is an awful question. This is mainly because of the third column that is titled $$fx$$. At no point in the question is either $$f$$ of $$x$$ defined!! Maybe I am being a bit pedantic, but to me because of this having a column titled $$fx$$ is meaningless and sloppy. Ok, I know that $$fx$$ seems to be often used in this context, but I really don’t like.

Surely this just sets a bad example for students… especially once they get to A-Level and beyond. Clarity of mathematical exposition is important, and it should make logical sense. It’s like if a student writes $$E(X)$$ without first defining the random variable $$X$$ – makes me want to cry a little!