Answer:
option (a) 4,000
Step-by-step explanation:
Data provided in the question:
cost of the equipment bought by Joe = $25,000
Estimated useful life = 5 years
Salvage value = $0
therefore,
The annual depreciation =

= $5,000 per year
Thus,
Book value on January 1, 2007
= Cost on January 1, 2006 - Depreciation till January 1, 2007
= $25,000 - ( $5,000 Ă— 1 )
= $20,000
Now,
The revised useful life is 6 years on January 1, 2007 but the 1 year has already been over
Thus,
remaining useful life = 6 - 1 = 5 years
Thus,
The revised depreciation =

= $4,000 per year
Hence,
The correct answer is option (a) 4,000