1. A tractor bought for $240,000 has an estimated residual value of $48,000, an estimated useful life of 40,000 hours, and was operated 2,660 hours during the first year. Determine: (a) the total amount to be depreciated over the life of the asset, (b) the amount of depreciation for the year, (c) the journal entry to record the year's depreciation, (d) the book value of the asset at the end of the first year, (e) explain why units of output may be preferred over straight line as a method of depreciating the tractor