P6-42. Estimating Useful Life and Percent Used Up The property and equipment section of the Abbott Laboratories 2015 balance sheet follows. Property and equipment, at cost ($ millions) Land...... Buildings.. Equipment.... Construction in progress. Less: accumulated depreciation and amortization..... Net property and equipment...... December 31 2015 2014 2013 $ 432 $457 $502 2,769 2,968 2,994 8,254 8,480 8,506 .928 727 868 12,383 12,632 12,870 6,653 $5,730 $ 5,935 $ 5,905 Classification Estimated Useful Lives Buildings........... Equipment The company also provides the following disclosure relating to the useful lives of its depreciable assets. Property and Equipment Depreciation and amortization are provided on a straight-line basis over the estimated useful lives of the assets. The following table shows estimated useful lives of property and equipment: 6,697 6,965 10 to 50 years (average 27 years) 3 to 20 years (average 11 years) During 2015, the company reported $871 million for depreciation expense. Required a.Compute the estimated useful life of Abbott Laboratories' depreciable assets. How does this compare with its useful lives footnote disclosure above? b.Compute the estimated percent used up of Abbott Laboratories' depreciable assets. How do you in- terpret this figure?