Answer:
The correct answer is option a.
Explanation:
The monthly total revenue is $5,000.
The marginal cost of producing 19th, 20th and 21st unit is $200.
Laura will earn profit if the price is able to cover marginal cost.
Total revenue is the product of price and quantity.
Price of cake when Laura produces 19 units
=
=
= $263.15
Price of cake when Laura produces 20 units
=
=
= $250
Price of cake when Laura produces 21 units
=
=
= $238.09
So we see that the price is able to cover marginal cost till 21st units, so Laura should produce more than 20 units and go on producing till price becomes equal to marginal cost.