Your firm spends $$534,000$ per year in regular maintenance of its equipment. Due to the economic downturn, the firm considers forgoing these maintenance expenses for the next $3$ years. If it does so$,$ it expects it will need to spend $$1\mathrm{.}9$ million in year $4$ replacing failed equipment.

a$.$ What is the IRR of the decision to forgo maintenance of the equipment?

b$.$ Does the IRR rule work for this decision?

c$.$ For what costs of capital $($COC$)$ is forgoing maintenance a good decision?