11. The air conditioner line is now to be run with JIT. In order to stabilize the planning for components, the GHI Company committed to producing exactly 125 units per each day in the week.

Productivity on the air conditioner line started at a somewhat low level, but has been steadily increasing. At the outset, the four-person line could assemble 125 units per day, but it required 10.5 hours per day to do so (2.5 hours of overtime). After six weeks (3,600 units cumulative) the team could assemble 125 units with little or no overtime. Thereafter, the team followed a classic learning curve (90 percent) pattern. A 90 percent learning curve implies that for every doubling of output, the time required to produce a unit decreases by 10 percent. At about 7,000 units cumulative, the daily time requirement to assemble 125 units fell to 7.2 hours.

a. What would be a good estimate of the cumulative average time for the first 3,600 units?