You are an inexperienced Excel user and don’t know how to create your own formulas. You want to use one of the preconfigured formulas but it doesn’t appear in the Formulas tab ribbon. What can you do?

Answer 1

Why are you not trying to answer these yourself? You must have been given a text (book or online) to study from. If you haven't, you should invest in a copy of Excel for Dummies (and no, that's not meant to be insulting; it's an excellent book).