A professional organization is planning to conduct a series of one-day continuing education programs in various cities. The projected costs related to these programs are
 

Promotional advertising$1,250 per program
Instructor’s fee$ 750 per program
Instructional materials$ 12 per participant
Hotel Charges: 
       Room rental and setup fee$ 400 per program
       Continental breakfast$ 10 per participant
       Lunch$ 25 per participant
       Refreshment breaks$ 8 per participant
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The hotel requires a $200 nonrefundable deposit on the room rental and setup fee 75 days prior to the program. At about the same time, the promotional advertising materials are developed, prepared, and mailed to potential participants, and a 20% payment is made to ensure the services of an instructor.  The instructor keeps this 20% payment even if the program is canceled and receives the balance of the fee at the conclusion of the program.  The remaining hotel fees and charges, as well as the cost of instructional materials, are paid at the conclusion of the program.
The capacity for each program is 100 persons, but past attendance for similar programs has averaged 80 persons.
Approximately ten days before the scheduled date of one program, only 25 individuals had registered for the program.  All fees had been paid as scheduled.  The director of the program decided to review the costs to determine whether the program should be canceled.  Which of the following cost-estimation equations should be used to determine the additional costs that would be incurred if the program were not canceled?
A. $1,600 plus ($55 times the number of participants).
B. $119 times the number of participants.
C. $2,400 plus ($55 times the number of participants).
D. $800 plus ($55 times the number of participants).
Answer：D
D is corrent. This response appropriately omits the costs which have already been incurred—promotional advertising ($1,250), the 20% down payment to the instructor ($750 × .2 = $150), and the nonrefundable room rental and setup fee ($200)—from the fixed cost calculations [$2,400 – ($1,250 + $150 + $200) = $800] because they are sunk costs. The variable cost figure is still relevant and, thus, is unchanged.