1. Machinery acquired new on January 1 at a cost of $50,000 was estimated to have a useful life of 10 years and a residual salvage value of $20,000. Straight-line depreciation was used. On January 1, following six full years of used of the machinery, management decided that the estimate of useful life had been too long and the machinery would have to be retired after two more years, that is, at the end of the eighth year of service. Under the revised estimate, the depreciation expenses for the seventh year of use would be:
   1. $6,000
   2. $8,000
   3. $11,000
   4. $12,000