$4.$Gross margin is one measure of profitability. Before adding the wall hammer, pitons were the only product the company manufactured. The financial results for selling $4,200$ pitons per month appear below $($Table $1)$ and show a gross margin of $5,4\%.$ Now, assuming the rock hammers have been added and employing the estimates and assumptions provided in the case, what will be the unit gross margins for EACH of the two product lines?

Table $1$

Volume

$50,400$

Revenue

$$529,200$

Materials

$$73,080$

Direct Labor

$$345,000$

Factory Overhead

Supplies

$$5,544$

Power

$$29,808$

Depreciation

$$14,355$

Occupancy

$$33,000$

Total Manufacturing costs

$$500,787$

Gross Margin

$$28,413$

$5\mathrm{.}4\%$

$5.$Based on your analysis, would you recommend expanding the product line? Why?