21) Marginal analysis involves undertaking an activity A) until its marginal costs start declining. B) only when its marginal benefits are positive. C) until its marginal benefits equal marginal costs. D) only if its marginal costs are greater than its marginal benefits. 22) The revenue received from the sale of ________ of a product is a marginal benefit to the firm. A) an additional unit B) the total number of units C) no units D) only profitable units 23) Making optimal decisions “at the margin” requires A) making decisions according to one’s whims and fancies. B) making consistently irrational decisions. C) weighing the costs and benefits of a decision before deciding if it should be pursued. D) making borderline decisions. 24) Making “how much” decisions involve A) calculating the total benefits of the activity and determining if you are satisfied with that amount. B) calculating the total costs of the activity and determining if you can afford to incur that expenditure. C) calculating the average benefit and the average cost of an activity to determine if it is worthwhile undertaking that activity. D) determining the additional benefits and the additional costs of that activity. 25) The extra cost associated with undertaking an activity is called A) net loss. B) marginal cost. C) opportunity cost. D) foregone cost. 26) DeShawn’s Detailing is a service that details cars at the customers’ homes or places of work. DeShawn’s cost for a basic detailing package is $40, and he charges $75 for this service. For a total price of $90, DeShawn will also detail the car’s engine, a service that adds an additional $20 to the total cost of the package. What is DeShawn’s marginal benefit if he sells a basic detailing package? A) $35 B) $75 C) He makes a marginal loss of $15, not a marginal benefit. D) The marginal benefit cannot be determined.  27) DeShawn’s Detailing is a service that details cars at the customers’ homes or places of work. DeShawn’s cost for a basic detailing package is $40, and he charges $75 for this service. For a total price of $90, DeShawn will also detail the car’s engine, a service that adds an additional $20 to the total cost of the package. What is the marginal cost of adding the engine detailing to the basic detailing package? A) $20 B) $30 C) $60 D) $60 plus the value of his time 28) DeShawn’s Detailing is a service that details cars at the customers’ homes or places of work. DeShawn’s cost for a basic detailing package is $40, and he charges $75 for this service. For a total price of $90, DeShawn will also detail the car’s engine, a service that adds an additional $20 to the total cost of the package. Should DeShawn continue to offer the engine detailing service? A) yes, he still makes a profit by selling the engine detailing service with the basic detailing package B) yes, but only if he raises the price of the basic detailing package C) no, his marginal benefit is less than his marginal cost D) More information is needed for DeShawn to make this decision. 29) Refer to Scenario 1-1. Using marginal analysis terminology, what is another economic term for the incremental revenue received from the sale of the last 3,000 cell phones? A) gross earnings B) marginal revenue C) sales revenue D) gross profit 30) Refer to Scenario 1-1. Using marginal analysis terminology, what is another economic term for the incremental cost of producing the last 3,000 cell phones? A) marginal cost B) operating cost C) explicit cost D) Any of the above terms are correct.