b$.$ How long should it take to complete the $10$ th unit?

c$.$ Estimate the average time per unit for the $25$ units.

The labor cost to produce a certain item is $$8\mathrm{.}50$ per hour. Job setup costs $$50$ and material costs

are $$20$ per unit. The item can be purchased for $$88\mathrm{.}50$ per unit. The learning rate is $90$ percent.

Overhead is charged at a rate of $50$ percent of labor, materials, and setup costs.

a$.$ Determine the unit cost for $20$ units, given that the first unit took five hours to complete.

b$.$ What is the minimum production quantity necessary to make production cost less than pur$-$

chase cost?

A firm has a training program for a certain operation. The progress of trainees is carefully moni$-$