25 As part of an R&D project, it is required to produce 60 circuit boards using a specific piece of equipment. According to the equipment specification, its design capacity is 0.4 board per hour. However, past experience indicates that significantly more time will be required.

In particular, the following frequency data were collected over a 1-week period when the machine was working on other jobs.

Activity Frequency Machine is working on a job 67 Parts are being fed to the machine 6 Maintenance is being performed 9 Machine is waiting for parts 22

a. Estimate the actual machine capacity.

b. How long will it take to complete the 60 boards?

c. If you want the capacity estimate to be within of the true value with a 95% level of confidence, then what should the sample size be? Assume that the capacity estimate is normally distributed.