Compute the payback period for the investment of $($a$)$ Problem $8\mathrm{.}3,($b$)$ Problem $8\mathrm{.}16,($c$)$ Problem

$8\mathrm{.}18.$ Ans. $($a$)$ PBP $=11$ years; $($b$)$ PBP $=8$ years; $($c$)$ PBP $=4\mathrm{.}17$ years