The 2019 income statement and balance sheet (excerpts) for Katy Co. are below.

Katy Co.

Consolidated Statements of Income

Year ended December 31,	2019	2018	2017
(In millions)
Revenues	$19,829	$21,967	$23,239
Operating expenses:
Compensation and benefits	4,769	5,043	5,023
Purchased services	2,418	2,546	2,592
Depreciation and amortization	2,128	2,001	2,123
Fuel	1,934	2,656	4,478
Equipment rents	766	801	867
Materials and other	1,129	1,196	1,143
Total operating expenses	13,144	14,243	16,226
Operating income	6,685	7,724	7,013
Interest expense	992	928	833
Other expense, net	0	21	11
Income before income taxes	5,693	6,775	6,169
Income tax expense	2,124	2,527	2,300
Net income	$ 3,569	$ 4,248	$ 3,869

Katy Co.

Consolidated Balance Sheets

December 31,	2019	2018
(in millions)
Current assets
Cash and cash equivalents	$ 3,218	$ 2,329
Accounts receivable, net	1,272	1,198
Materials and supplies	825	829
Current portion of deferred income taxes	0	245
Other current assets	235	337
Total current assets	5,550	4,938
Property and equipment, net of accumulated depreciation of $6,130 and $4,845, respectively	61,250	59,510
Goodwill	14,845	14,845
Intangible assets, net	430	468
Other assets	2,047	1,942
Total assets	$84,122	$81,703

The footnotes to the financial statements included the following:

Property and equipment, net (in millions), and the corresponding ranges of estimated useful lives were as follows:

December 31,	2019		2018		2019 Range of Estimated Useful Life
Land for transportation purposes	$ 6,063		$ 6,037		---
Track structure	22,287		21,200		15-50 years
Other roadway	25,990		24,767		7-100 years
Locomotives	8,338		7,794		7-35 years
Freight cars and other equipment	2,755		2,629		8-40 years
Computer hardware, software, and other	982		897		6-9 years
Construction in progress	965		1,031		---
Total cost	67,380		64,355
Less accumulated depreciation and amortization	(6,130	)	(4,845	)
Property and equipment, net	$61,250		$59,510

Required:

a.	What proportion of total assets, does the company hold as property and equipment in 2019 and 2018? Does this surprise you?
b.	Compute property and equipment turnover for 2019 and 2018. Property and equipment, net for 2017 was $55,806 million. Explain this ratio.
c.	Estimate the useful life on average for the company depreciable assets at year-end 2019. Which of the assets listed in the footnote explain this estimated useful life?