you should use functions, formulae, charts etc. within Excel (or another computer package) rather than doing calculations or producing displays by hand (though this would be a lot better than nothing at all).
Your report should be written according to the guidelines given in the document “Report Advice” available on Moodle. This is important and a fairly high proportion of your mark will depend upon this (20%). A report that contains accurate calculations but does not convey them in an appropriate way will not receive a high mark.