Answer:
a. Incremental cost of making the part $
Variable cost (50,000 units x $2.50) = 125,000
Attributable fixed cost = 50,000
Incremental cost 175,000
b. Incremental cost of buying the part from outside
= 50,000 units x $3.70
= $185,000
Explanation: The incremental cost of making the part is the total relevant cost of production, which involves variable cost and attributable fixed cost.
The incremental cost of buying the component refers to cost of buying the part from outside.