(b) Rohm and Haas reported depreciation expense of $422 million in 2005. Estimate the useful life, on average, for its depreciable PPE assets. (Round your answer to two decimal places.)

(c) By what percentage are Rohm and Haas' assets "used up" at year-end 2005? (Round your answer to two decimal places.)

$ 141 Interpreting and Applying Disclosures on Property and Equipment Following are selected disclosures from the Rohm and Haas Company (a specialty chemical company) 2005 10-K. Land, Building and Equipment, Net (in millions) 2005 2004 Land $ 139 Buildings and improvements 1,683 1,744 Machinery and equipment 5,570 5,656 Capitalized interest 329 320 Construction in progress 168 166 Land, Building and Equipment, Gross 7,889 8,027 Less: Accumulated depreciation 5,208 5,098 Total $ 2,681 $ 2,929 The principal lives in years) used in determining depreciation rates of various assets are: buildings and improvement (10-50); machinery and equipment (5-20); automobiles, trucks and tank cars (3-10); furniture and fixtures, laboratory equipment and other assets (5-10); capitalized software (5-7). The principal life used in determining the depreciation rate for leasehold improvements is the years remaining in the lease term or the useful life (in years) of the asset, whichever is shorter. IMPAIRMENT OF LONG-LIVED ASSETS Long-lived assets, other than investments, goodwill and indefinite-lived intangible assets, are depreciated over their estimated useful lives, and are reviewed for impairment whenever changes in circumstances indicate the carrying value of the asset may not be recoverable. Such circumstances would include items such as a significant decrease in the market price of a long-lived asset, a significant adverse change in the manner the asset is being used or planned to be used or in its physical condition or a history of operating or cash flow losses associated with the use of the asset ... When such events or changes occur, we assess the recoverability of the asset by comparing the carrying value of the asset to the expected future cash flows associated with the asset's planned future use and eventual disposition of the asset, if applicable...We utilize marketplace assumptions to calculate the discounted cash flows used in determining the asset's fair value. In 2005, $81 million of asset impairments were recognized for the impairment of certain finite-lived intangible assets and fixed assets across several of our chemical businesses and our Electronic Materials segment