Answer:
The minimum average cost per dulcimer is 150 and the minimum cost is $180.
Step-by-step explanation:
The given cost function is

Differentiate the function C(x) with respect to x.


Equate C'(x)=0, to find the critical values.



Divide both sides by 0.4.


Differentiate the function C'(x) with respect to x.


At x=1.5

The value of double derivative is positive. It means the function is minimum at x=1.5 hundred.
1.5 hundred = 150
Substitute x=1.5 in the given function to find the minimum average cost.


The minimum cost is 1.8 hundred dollars.
1.8 hundred dollars = $180
Therefore, the minimum average cost per dulcimer is 150 and the minimum cost is $180.