Im not sure if i ever did exactly what your describing, but I recall doing something similar in which the questions were in excel and I had to put my answers in the workbook and send back. In my experience, the questions weren’t difficult, some were just basic algebra. They are really looking for accuracy, excel knowledge, and timeliness.

For accuracy, it’s really more about interpreting the question and applying calculations correctly. There will most likely be lingo you haven’t seen before with some definitions, but you just need to be able to internet this to do a simple calculation. Don’t go crazy with over complicated formulas in excel, but when possible use the most robust formula that makes sense(eg use a sumproduct instead of a bunch of sums). Finally, don’t submit late. It’s better in this situation to submit what you have done than to spend an extra minute or too and submit it late because this is a consultancy. Again not sure on the format of this, but if you have to send it back in an email, draft an email prior to starting the quiz.