If Patti increases her production of pizzas from 7 to 16 pizzas per day, then her marginal cost is $2.89.
Marginal cost refers to the additional cost incurred by producing one more unit of a good or service.
Marginal cost = Δ in Total cost (TC) / Δ in Output (Q). Note that TC = TFC + TVC where TFC is constant at all output levels.
When Output is 7, L = 2. So, the total cost is:
= $40 + ($26 * 2)
= $40 + 52
= $92
When Output is 16, L = 3. So, the total cost is:
= $40 + ($26 * 3)
= $40 + 78
= $118.
The Marginal cost = Δ in Total cost (TC) / Δ in Output (Q).
MC = 118 - 92 / 16 - 7
MC = 26 / 9
MC = 2.88888888889
MC = 2.89.