An activity-based costing system that is designed for internal decision-making will not conform to generally accepted accounting principles because: some manufacturing costs (i.e., the costs of idle capacity and organization-sustaining costs) will not be assigned to products. some nonmanufacturing costs are assigned to products. first-stage allocations may be based on subjective interview data. all of these are reasons why an activity-based costing system that is designed for internal decision-making will not conform to generally accepted accounting principles