A batch of $75$ parts is to be nickel$-$plated in a barrel plating operation. The parts are identical, each with a surface area A $=5\mathrm{.}3$ in$2.$ The plating process applies a current $=120$ amps, and the batch takes $20$ min to complete.

Determine the average plating thickness on the parts. $($X$.$XXXXX in$)$

Tolerance $+/-0\mathrm{.}00005$