Applying the Cumulative Average Time Learning Curve

Propeller Inc. plans to manufacture a newly designed high$-$technology propeller for airplanes. Propeller forecasts that as workers gain experience, they will need less time to complete the job. Based on prior

experience, Propeller estimates a $70\%$ cumulative average time learning curve and has projected the following costs.

a$.$ If Propeller manufactures four propellers, what would the total manufacturing costs be$?$

b$.$ If Propeller manufactures eight propellers, what would the total manufacturing costs be$?$

c$.$ Calculate the cumulative average cost of producing the eighth propeller as a percentage of the cost

of producing the first propeller.