Answer:
The old machine should be replaced. The rationales are given as below:
<u>* In case we retain the old machine, total cost over five year will be the sum of the below cost items:</u>
- Depreciation of the old machine = Current book value of the old machine = $90,000 ( as the machine has remaining useful life of 5 years and no salvage value at the end of 5 year is given)
- 5-year variable manufacturing cost = annual variable manufacturing costs * 5 = 600,000 * 5 = $3,000,000
<u>=> Total cost over five year = $3,000,000 + $90,000 = $3,090,000</u>
<u>* In case we replace the old machine, total cost over five year will be the sum of the below cost items:</u>
- Loss of selling old machine = Proceed from selling old machine - Book value of old machine = 30,000 - 90,000 = $60,000
- Depreciation of the new machine = Cost of the new machine = 400,000 ( as the machine has useful life of 5 years and no salvage value at the end of 5 year)
- 5-year variable manufacturing cost = annual variable manufacturing costs * 5 = 500,000 * 5 = $2,500,000
<u>=> Total cost over five year = $2,500,000 + $400,000 + 60,000 = $2,960,000</u>
<em><u>So, as replacing the machine will result in lower cost in comparison to retaining it ( $2,960,000 in comparison to $3,090,000), we should replace the old machine.</u></em>
Explanation: