Irving and his wife Gertrude decide to take their life savings of $20,000 to buy a small retail shop. They plan to make and sell tie-dyed, University of Kentucky T-shirts. They hire a professional tie-dyer for $6. 00 an hour who makes 20 t-shirts per hour. The following are needed to produce the shirts: dye, costing $1 per shirt, plain white t-shirts costing $1 each and an industrial washing machine for $1000.
What is the marginal cost of producing one additional T-shirt?
a) $8. 00
b) $12. 30
c) $2. 30
d) $2. 00