NO.PZ2018062018000056
问题如下：
Company M uses the double-declining balance method to amortize a $120,000 patent, which has a useful life of 4 years. If it shifts to straight-line method, the net book value at the end of Year 3 will witness a difference of:
选项：
A.
$15,000
B.
$10,000
C.
$30,000
解释：
A is correct.
Net book value at the end of Year 3 based on straight-line method =$120,000 - ($120,000×3/4) = $30,000
Net book value at the end of Year 3 based on double-declining balance method = $120,000×(1–0.5)3 = $15,000
The difference = $30,000 - $15,000 = $15,000
0.5是怎么来的 DDB的公式讲解一下
