... minute.A first try at a formula might beThis is unwieldy as formulas go, so statisticians use abbreviations. A com-monly used abbreviation for “Number” is x. A typical abbreviation for “Amount of ... for- mula becomesAnother abbreviation, used throughout statistics, stands for Sum of. It’s the uppercase Greek letter for S. It’s pronounced “sigma” and it looks like this: Σ. Here’s the formula ... the formula won’t work.What about the average for Green Squares in cell D21? Figure 4-4 shows the completed dialog box for AVERAGEIFS, which can work with more than one criterion. The formula...