of 1 Killington Koal Company, Inc. purchased a new mining machine at a total cost of $1,080,000 on the first day of its fiscal year. The firm estimates that the machine has a useful life of 6 years or 6,800,000 tons of coal and a residual value of $60,000 at the end of its useful life. The following schedule indicates the actual number of tons of coal mined with the machine per year: (Click the icon to view the schedule.) Requirement a. Prepare the depreciation schedule for the machine assuming that Killington Koal used the straight-line method. End-of-Year Depreciation Expense Accumulated End-of-Year Net Original Cost Depreciation Book Value (NBV) Year 1 $ 170,000 1,080,000 $ 170,000 $ 910,000 Year 2 170,000 1,080,000 340,000 740,000 Year 3 170,000 1,080,000 510,000 570,000 Year 4 170,000 1,080,000 680,000 400,000 Year 5 170,000 1,080,000 850,000 230,000 Year 6 170,000 1,080,000 1,020,000 60,000 $ 1,020,000 Total