Your roommate's long hours in the chem lab finally paid off- she discovered a secret formula that lets people do an hour's worth of studying in 5 minutes. So far, she's sold 200 doses and faces the following average total cost schedule

Question

Your roommate's long hours in the chem lab finally paid off- she discovered a secret formula that lets people do an hour's worth of studying in 5 minutes. So far, she's sold 200 doses and faces the following average total cost schedule 
Quantity Average total cost 
199 doses $199 
200 $200 
201 $201 
If a new customer offers pay your roommate 
$300 for one dose, should she make one more. Explain.

Your figures indicate that it costs your roommate $1 to make 1 dose. It seems to be a no-brainer for her to make one more dose for a sale of $300. If she needs to make 200 doses for $200, she still reaps a great profit by selling one dose for $300.