Answer to Question 1
1. The variable costs required to manufacture 150,000 starter assemblies are
Direct materials 400,000
Direct manufacturing labor 300,000
Variable manufacturing overhead 200,000
Total variable costs 900,000
The variable costs per unit are 900,000 150,000 = 6.00 per unit.
Let X = number of starter assemblies required in the next 12 months.
The data can be presented in both all data and relevant data formats:
All Data Relevant Data
Alternative 1:
Make Alternative 2:
Buy Alternative 1:
Make Alternative 2: Buy
Variable manufacturing costs
Fixed general manufacturing overhead
Fixed overhead, avoidable
Division 2 manager's salary
Division 3 manager's salary
Purchase cost, if bought from
Tutwiler Electronics
Total costs
6X
300,000
200,000
80,000
100,000
680,000
+ 6X
300,000
100,000
8X
400,000
+ 8X 6X
200,000
80,000
100,000
380,000
+ 6X
100,000
8X
100,000
+ 8X
The number of units at which the costs of make and buy are equivalent is
All data analysis: 680,000 + 6X = 400,000 + 8X
2X = 280,000
X = 140,000
or
Relevant data analysis: 380,000 + 6X = 100,000 + 8X
2X = 280,000
X = 140,000
Assuming cost minimization is the objective, then
If production is expected to be less than 140,000 units, it is preferable to buy units from Tutwiler.
If production is expected to exceed 140,000 units, it is preferable to manufacture internally (make) the units.
If production is expected to be 140,000 units, Denver should be indifferent between buying units from Tutwiler and manufacturing (making) the units internally.
2. The information on the storage cost, which is avoidable if self-manufacture is discontinued, is relevant; these storage charges represent current outlays that are avoidable if self-manufacture is discontinued. Assume these 100,000 charges are represented as an opportunity cost of the make alternative. The costs of internal manufacture that incorporate this 100,000 opportunity cost are
All data analysis: 780,000 + 6X
Relevant data analysis: 480,000 + 6X
Alternatively stated, we would add the following line to the table shown in requirement 1 causing the total costs line to change as follows:
All Data Relevant Data
Alternative 1: Alternative 2: Alternative 1: Alternative 2:
Make Buy Make Buy
Outside storage charges 100,000 0 100,000 0
Total costs 780,0001 + 6X 400,000 + 8X 480,0002 + 6X 100,000 + 8X
1780,000 = 680,000 + 100,000 2480,000 = 380,000 + 100,000
The number of units at which the costs of make and buy are equivalent is
All data analysis: 780,000 + 6X = 400,000 + 8X
2X = 380,000
X = 190,000
Relevant data analysis: 480,000 + 6X = 100,000 + 8X
2X = 380,000
X = 190,000
If production is expected to be less than 190,000, it is preferable to buy units from Tutwiler. If production is expected to exceed 190,000, it is preferable to manufacture the units internally.
Answer to Question 2
C