Using the data from Problem E.14, how long will it take to complete the 12th plane? The 15th plane? How long will it take to complete planes 12 through 15 inclusive? At $40 per hour, what can Alwan, as purchasing agent, expect to pay for planes 12 through 15?

Data from problem E.14

Suad Alwan, the purchasing agent for Dubai Airlines, is interested in determining what he can expect to pay for airplane number 4 if the third plane took 20,000 hours to produce. What would Alwan expect to pay for plane number 5? Number 6? Use an 85% learning curve and a $40-per-hour labor charge.