Marginal cost
a. is the increase in total cost resulting from production of one additional unit of output.
b. is the cost of the marginal unit of output.
c. all of the above are correct.
d. and the average cost curve are u-shaped.

Pestiferous manufacturing produces a chemical pesticide and uses process costing. there are three processing departmentslong dash​mixing, ​refining, and packaging. on january​ 1, the first departmentlong dashmixinglong dashhad no beginning inventory. during​ january, 48,000 fl. oz. of chemicals were started in production. of​ these, 40,000 fl. oz. were​ completed, and​ 8,000 fl. oz. remained in process. in the mixing​ department, all direct materials are added at the beginning of the production​ process, and conversion costs are applied evenly throughout the process. at the end of​ january, the equivalent unit data for the mixing department were as​ follows: units equivalent units equivalent units units to be accounted for direct materials costs conversion costs completed and transferred out ​40,000 ​40,000 ​40,000 ending​ work-in-process* ​8,000 ​8,000 ​3,520 ​48,000 ​48,000 ​43,520 ​* percent complete for conversion​ costs: 44% in addition to the​ above, the cost per equivalent unit were​ $1.35 for direct materials and​ $5.30 for conversion costs. using this​ data, calculate the full cost of the ending wip balance in the mixing department. the​ weighted-average method is used.