While waiting in line to buy two tacos at 75 cents each, and a medium drink for 80 cents, Emma notices that the restaurant has a value meal containing three tacos and a medium drink all for $2.50 . For Emma, the marginal cost of purchasing the third taco would be

As a result of the decrease in donut prices at Real Yum Donuts, Dippin Donuts managers discover that the demand for their donuts has: a. increased

b. decreased. c. not changed. d. none of the above

Coal is considered to be a non-renewable energy source. Which of the following statements is correct?

a. Coal is an unlimited resource. b. Coal is a scarce resource. c. Coal is a non-scarce resource. d. Coal is not a resource.