Natcan Inc. manufactures cans for the canned food industry. The operations manager of a can manufacturing operation wants to conduct a cost study investigating the relationship of tin content in the material (can stock) to the energy cost for enameling the cans. The enameling was necessary to prepare the cans for labeling. A higher percentage of tin content in the can stock increases the cost of material. The operations manager believed there was a relationship between the tin content and energy costs for enameling. During the analysis period, the amount of tin content in the steel can stock was increased for every month, from April to September. The following operating reports were available from the controller:

 

April

May

June

July

August

September

Energy

$ 13,000

$ 28,800

$ 24,200

$ 14,000

$ 16,200

$ 15,000

Materials

12,000

30,000

28,600

18,900

25,200

29,000

Total cost

$ 25,000

$ 58,800

$ 52,800

$ 32,900

$ 41,400

$ 44,000

Units produced

/50,000

/120,000

/110,000

/70,000

/90,000

/100,000

Cost per unit

$ 0.50

$ 0.49

$ 0.48

$ 0.47

$ 0.46

$ 0.44

Differences in materials unit costs were entirely related to the amount of tin content.

Interpret this information and report to the operations manager your recommendations with respect to tin content.