Question

How is short period marginal cost estimated?

Answer 1

Short Period Marginal Cost can be estimated either from Total Variable Cost or from Total Cost. Marginal cost is an additional cost. 

MC can be calculated by the following ways: 
MC = TC_n – TC_n-1
= (TFC_n + TVC_n) – (TFC_n-1 + TVC_n-1)
= TVCn – TVC_n-1
(TFC_n = TFC_n-1, because TFC is constant).