12. A manager is trying to estimate the appropriate learning curve for a certain job. The manager notes that the first four units had a total time of 30 minutes. Which learning curve would yield approximately this result if the first unit took 10 minutes?

13. A job has a 70 percent learning curve. If the first unit took 10 hours to complete, the third unit should take roughly how many hours?

14. A job has an 80 percent learning curve. If the first unit took 50 hours to complete, the third unit should take roughly how many hours?

17. Unit times for a job exhibit a learning effect. If the second unit took 30 hours, and the fourth unit took 21 hours, roughly how many hours would you estimate the third unit took?

23. A job is expected to have a learning curve of 90 percent. The third unit required 16 hours. The twelth unit should take approximately how many hours?

31. A job has an 80 percent learning curve. The second unit required 12 hours to complete. Approximately how many hours will be devoted to the first five units (including those already completed)?

34. A manager is trying to estimate the learning rate for a new job. The first unit took 16 hours and the fourth unit required about 13 hours. The learning rate is:

39. Suppose the first unit of output required 900 labor hours, and the second unit required only 810. At this rate, how many more units must be produced before labor requirements are less than 700 hours?