Costs associated with two alternatives, code-named Q and R, being considered by Albiston Corporation are listed below:

Alternative Q Alternative R

Supplies costs $91,000 $91,000

Power costs $55,000 $54,200

Inspection costs $47,000 $54,200

Assembly costs $56,000 $56,000

Required:

a. Which costs are relevant and which are not relevant in the choice between these two alternatives?

b. What is the differential cost between the two alternatives?