$3-36.$ Find the average time per unit required to produce

the first $30$ units, if the slope parameter of the learning

rate is $92\%$ and the first unit takes $460$ hours.

$($a$)330\mathrm{.}693($b$)305\mathrm{.}5404($c$)245$

$($d$)347\mathrm{.}3211$