Output from a process contains $0\mathrm{.}04$ defective unit. Defective units that go undetected into final assemblies cost $$23$ each to replace. An detect and remove all defectives, can be established to test these units. However, the inspector, who can test $18$ units per hour, is paid $$8$ per hour, including fringe benefits. Assume that the line will operate at the same rate $($i$.$e$.,$ the current production rate$)$ regardless of whether or not the inspection operation is added.

$a-1.$ Without the inspector, what is the current hourly cost of defects? $($please round to two decimal places$)$

$56\mathrm{.}16$

$16\mathrm{.}56$

$13\mathrm{.}56$

$19\mathrm{.}25$