$4.$ Calculating present value with infinite income streams

Read No Evil $($RNE$)$ is a firm specializing in the destruction of sensitive documents. An industrial paper shredder costs $$8,000.$ If bought, it would raise RNE's revenue by an additional $$400$ per year. The machine is designed to last forever and never require maintenance. If the firm does not purchase the machine, it will put the money into an interest$-$bearing bank account.

At which interest rates would RNE be willing to buy the machine? Check all that apply.

$1\%$

$12\%$

$6\%$

$4\%$