Final answer:
Advertising expenses are a common cost that normally cannot be assigned to products on a segmented income statement except on an arbitrary basis.
Step-by-step explanation:
A common example of a cost that normally cannot be assigned to products on a segmented income statement except on an arbitrary basis is advertising expenses. Advertising costs are typically incurred to promote a brand or product line as a whole, rather than being directly attributable to individual products. Since segmented income statements focus on the profitability of specific product lines or segments, it is difficult to allocate advertising costs in a way that accurately reflects their impact on individual products. Therefore, advertising expenses are often excluded or allocated based on arbitrary methods in segmented income statements.