Answer:
0.6
Step-by-step explanation:
Given that the manufacturer has a total cost in dollars of producing x dozen pens in one day given by

Marginal cost is the derivative of the total cost function with respect to the output variable which is x here.
MC = C'(x)
= 2 - 2 × 0.01x
MC = 2 - 0.02x
MC at a production level of 70 dozen pens is:
MC (x = 70) = 2 - 0.02 × 70
= 2 - 1.4
= 0.6
Therefore, marginal cost at a production level of 70 dozen pens is 0.6.