During 1998 Federal Express reported the following information (in millions):

net sales of $13,255, net income of $421, and depreciation expense of $845. Its balance sheet also showed total assets at the beginning of the year of $7,625 and total assets at the end of the year of $8,433; beginning plant assets (at cost) of $9,819, ending plant assets (at cost) of $11,064, and accumulated depreciation at year-end of $5,863.

Instructions Calculate

(a) average useful life of plant assets,

(b) average age of plant assets, and (c)

asset turnover ratio.