At the beginning of 2015, SD Corporation acquired machinery that cost $100 000 and had an anticipated useful life of 10 years. SD Corporation depreciated this machinery for 2015 and 2016, using the straight-line method. During 2017, it decided to change to the reducing balance method of depreciation. 

1. Prepare the journal entry to record depreciation expense for 2016, using the straight-line method. 

2. Prepare the journal entry to record depreciation expense for 2016 using the reducing balance method, at a rate of 20 per cent. 

3. Show the effects of changing from the straight-line method to the 20 per cent reducing balance method on: 

a. The net profit before tax for 2017 

b. The total assets for 2017. 

4. In what circumstances is the use of reducing balance depreciation more appropriate than using the straight-line method?