To illustrate the approximately relevant ABC concept, consider the data for Sencillo
Electronics presented in Exhibit 4-16 on page 144. Sencillo produces two types of
wafers: Wafer A and Wafer B. A wafer is a thin slice of silicon used as a base for integrated
circuits or other electronic components. The dies on each wafer represent a particular
configuration—a configuration designed for use by a particular end product.
Sencillo produces wafers in batches, where each batch corresponds to a particular type
of wafer (A or B). In the wafer inserting and sorting process, dies are inserted, and the
wafers are tested to ensure that the dies are not defective. From Exhibit 4-16, we see
that the activity-based costs for Wafer A and Wafer B are $800,000 and $1,200,000,
respectively. These activity-based costs are calculated using the 12 drivers. We also see
that four activities (developing test programs, testing products, inserting dies, and purchasing
materials) account for 75 percent of the total costs. The cost assignments using
the cost pools and the associated drivers of these four activities are shown in Exhibit
4-17 on page 145. The costs of the inexpensive activities are allocated to the four expensive
activities in proportion to their original cost.