Managing for Quality and Performance Excellence 10th Edition by James Evans ,William Lindsay

Exercise 67

Note: Data sets for several problems are available in the Excel workbook C07Data in the Student Companion Site for this chapter. Click on the appropriate worksheet tab as noted in the problem (e.g., Prob. 7-5, etc.) to access the data.
The life of a Cellurific phone battery is normally distributed with a mean of 1,100 days and standard deviation of 60 days. Using the Excel functions (see Chapter 6), determine the following:
a. What fraction of batteries is expected to survive beyond 1,200 days?
b. What fraction will survive fewer than 995 days?
c. Draw a chart of the reliability function using Excel.
d. What length of warranty is needed so that no more than 10 percent of the batteries will be expected to fail during the warranty period?