The financial impact of IT systems downtime is a concern of plant operations management today. A survey of manufacturers examined the satisfaction level with the reliability and availability of their manufacturing IT applications. The variables of focus are whether the manufacturer experienced downtime in the past year that affected one or more manufacturing IT applications, the number of downtime incidents that occurred in the past year, and the approximate cost of a typical downtime incident. The results from a sample of 200 manufacturers are as follows:

• Sixty- two experienced downtime this year that affected one or more manufacturing applications.

• Number of downtime incidents: X-bar = 3.5, S = 2.0

• Cost of downtime incidents: X-bar = $18,000, S = $3,000.

a. Construct a 90% confidence interval estimate for the population proportion of manufacturers who experienced downtime in the past year that affected one or more manufacturing IT applications. 

b. Construct a 95% confidence interval estimate for the population mean number of downtime incidents experienced by manufacturers in the past year.

c. Construct a 95% confidence interval estimate for the population mean cost of downtime incidents.