A plant asset was purchased on January 1 for $47200 with an estimated salvage value of $10000 at the end of its useful life. The current year's depreciation expense is $3100 calculated on the straight-line basis and the balance of the Accumulated Depreciation account at the end of the year is $24800. The remaining useful life of the plant asset is 4 years. 15 years. 12 years. 8 years