For each of the following long-lived assets, select its nature and the related cost allocation concept. Asset Nature Cost Allocation Concept Building Equipment Intangible (1) Tractors (2) Land in use (3) Timber tract (4) Warehouse (5) New engine for old machine (6) Operating license (7) Production plant (8) Patent (9) Silver mine (10) Land held for sale Land Natural resource Other A three-year-old machine has a cost of $31,000, an estimated residual value of $1,000, and an estimated useful life of five years. The company uses straight-line depreciation. Calculate the net book value at the end of the third year. Net book value