Unit cost is per unit, could be per oz, or per bottle.
Since unit cost per bottle is already given, we assume unit cost required is per oz.
16oz costs $2.00
1 oz costs $X.
Cross multiply,
16X=1*2.00
X=2.00/16 = 0.125
The unit cost (of capacity of bottle) is $0.125 per oz of bottle capacity.
or
The unit cost of the bottle is $2 per bottle (as given in question).
