Final answer:
Statement 4) 'The cost of the new machine is greater than the book value of the old machine' is true. Managers should consider the cost of the new machine against not just the book value but also the present discounted value of future benefits and the sustainability aspects of the investment.
Step-by-step explanation:
When managers are examining a possible replacement of a machine they need to consider various financial factors including the book value of the old machine, its current disposal value, any loss on disposal, and the cost of the new machine.
With the information given: the book value of the old machine is 100,000, the current disposal value is 50,000, the loss on disposal would be 300,000 (which seems incorrect given the book value and disposal value), and the cost of the new machine is 600,000.
Looking at the numerical data, the cost of the new machine is indeed greater than the book value of the old machine. Hence, statement 4) 'The cost of the new machine is greater than the book value of the old machine' would be true. Statements 1), 2), and 3) are not correct based on the given values.
The managers should also consider other economic factors such as the present discounted value of future benefits from the new machine compared to the present costs, taking into account the broader implications of a sustainable economy and environmental considerations.