Which function is commonly used to calculate the average of a range of cells?

The function used to calculate the average of a range of cells is AVERAGE(). This function sums up all the numbers in the specified range and divides that total by the count of the numbers to provide the mean value. It is particularly useful in scenarios where you want to determine a central tendency from a set of data values.

In contrast, the SUM() function simply adds up all the numbers in a range without performing any division to find an average. COUNT() is used to count the number of entries in a range, ignoring any non-numeric cells, and does not provide a value that reflects the average. The MAX() function identifies the highest value in a range but does not contribute to determining the average at all. Thus, AVERAGE() is specifically designed for calculating the mean, which makes it the correct choice for this question.