You need to create the AD Sales measure. Which aggregation function should you use?

Sum would add all child values together, producing a total rather than an average, which misrepresents metrics like average daily sales at a parent level.

Average computes the mean of all non-empty leaf-level cells rather than averaging only the direct children in the hierarchy, giving an incorrect result for parent-level browsing.

ByAccount uses the aggregation function defined on the Account dimension's Type attribute, which is unrelated to computing an average of child members for the AD Sales measure.

AverageOfChildren is a semi-additive aggregation function in Analysis Services that calculates the average of a measure's child members rather than summing or averaging all leaf-level values. This is appropriate for 'AD' (Average of Daily) type measures such as AD Sales, where a monthly total should reflect the average of its daily children. Unlike Sum or Average, it respects the parent-child relationship in the time or other hierarchies involved.