The December 31, 2012, partial financial statements taken from the annual report for AT&T Inc. (T) follow.

Consolidated Statements of Income
Dollars in millions except per share amounts	2012	2011
Operating revenues
Wireless service	$ 59,186	$ 56,726
Data	31,798	29,560
Voice	22,619	25,126
Directory	1,049	3,293
Other	12,782	12,782
Total operating revenues	127,434	126,723
Operating expenses
Cost of services and sales (exclusive of depreciation and amortization show separately below)	55,215	54,836
Selling, general and administrative	41,079	41,382
Impairment of intangible assets	--	2,910
Depreciation and amortization	18,143	18,377
Total operating expenses	114,437	117,505
Operating income	12,997	9,218
Other income (expense):
Interest expense	(3,444)	(3,535)
Equity in net income of affiliates	752	784
Other income, net	134	249
Total other income (expense)	(2,558)	(2,502)
Income from continuing operations before income taxes	10,439	6,716
Income tax (benefit) expense	2,900	2,532
Income from continuing operations	7,539	4,184
Income from discontinued operations, net of tax	--	--
Net income	$ 7,539	$ 4,184

Consolidated Balance Sheets -- Liabilities and Equity Sections
Dollars in millions except per share amounts, December 31	2012	2011
Current liabilities
Debt maturing within one year	$ 3,486	$ 3,453
Accounts payable and accrued liabilities	20,911	19,956
Advanced billed and customer deposits	3,808	3,872
Accrued taxes	1,026	1,003
Dividends payable	2,556	2,608
Total current liabilities	31,787	30,892
Long-term debt	66,358	61,300
Deferred credits and other noncurrent liabilities:
Deferred income taxes	28,491	25,748
Post employment benefit obligation	41,392	34,011
Other noncurrent liabilities	11,592	12,694
Total deferred credits and other noncurrent liabilities	81,475	72,453
Stockholders' equity
Common stock ($1 par value, 14,000,000,000 authorized at December 31, 2012 and 2011; issued 6,495,231,088 at December 31, 2012 and 2011)	6,495	6,495
Additional paid-in capital	91,038	91,156
Retained earnings	22,481	25,453
Treasury stock (913,836,325 at December 31, 2012 and 568,719,202 at December 31, 2011, at cost)	(32,888)	(20,750)
Accumulated other comprehensive income	5,236	3,180
Noncontrolling interest	333	263
Total stockholders' equity	92,695	105,797
Total liabilities and stockholders' equity	$ 272,315	$270,442

Consolidated Statements of Stockholders' Equity -- Excerpts	2012
Amount in millions except per share amounts, December 31	Shares	Amounts
Common Stock
Balance at beginning of year	6,495	$ 6,495
Issuance of shares	--	--
Balance at end of year	6,495	$ 6,495
Additional Paid-In-Capital
Balance at beginning of year		$ 91,156
Issuance of treasury stock		120
Share-based payments		(78)
Share of equity method investee capital transactions		(160)
Change related to acquisition of interests held by non-controlling owners		--
Balance at end of year		$ 91,038
Retained Earnings
Balance at beginning of year		$25,453
Net income attributable to AT&T ($1.25 per diluted share)		7,264
Dividends to stockholders ($1.77 per share)		(10,196)
Other		(40)
Balance at end of year		$ 22,841
Treasury Shares
Balance at beginning of year	(568)	$(20,750)
Repurchase of common stock	(371)	(12,752)
Issuance of treasury stock	25	614
Balance at end of year	(914)	$(32,888)

(a) How much interest expense did AT&T incur during 2012?
$Answer million
(b) What is the book value of AT&T's interest-bearing debt at the end of 2012?
$Answer million
At the beginning of 2012?
Average debt for 2012? (Round to the nearest whole number)
(c) Estimate AT&T's 2012 pretax cost of debt capital. (Round your answer to one decimal place.)
(d) Estimate AT&T's 2012 effective (that is, average) tax rate from information in its income statement. (Round your answer to one decimal place.
(e) Using your rounded answer from (c) above, estimate AT&T's 2012 after-tax cost of debt capital. The company's stat tax rate is: 37% (Round your answer to one decimal place.)