Part 1 of 4 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.) Read the requirements.