How Many Hours at the Candy Stall? The opportunity cost of your time spent selling candy at your stall in a shopping mall is $15 per hour. Electricity costs $2 per hour, and the weekly rent is $300....

How Many Hours at the Candy Stall? The opportunity cost of your time spent selling candy at your stall in a shopping mall is $15 per hour. Electricity costs $2 per hour, and the weekly rent is $300. You normally stay open 11 hours per day (the mall is open 24/7).

a. What is the marginal cost of staying open for one more hour?

b. If you expect to sell 4 kilograms of candy in the 12th hour, earning $7 per kilogram, is it sensible to stay open for the extra hour?