Estimating Useful Life and Percent Used Up The property and equipment footnote from the Deere & Company Equipment and Operations segment follows. Property and Depreciation A summary of property and equipment at October 31 follows. Property and Equipment ($ millions) Useful Lives 2015 2014 (Years) Land $114 $120 Buildings and building equipment 23 2,794 3,037 Machinery and equipment 11 4,833 5,089 Dies, patterns, tools, etc 8 1,567 1,552 All other S 875 889 345 530 10,528 11,217 5,846 5,694 $4,682 $5,523 Construction in progress Total at cost Less accumulated depreciation Total "Weighted averages Total property and equipment additions in 2015, 2014 and 2013 were $666 million, $1,016 million and $1,158 million, and depreciation was $692 million, $696 million and $637 million, respectively. a. Compute the average useful life of Deere's depreciable assets at year-end 2015. Round answer to one decimal place. years b. Estimate the percent used up of Deere's depreciable assets at year-end 2015, Round answer to one decimal place (ex: 0.2345 23.5%)