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Some of the following examples use data sets in an electronic format. These files are located in the "Tutorial" directory on your CD. Example 1Ten units are placed on a test stand. The following failures were recorded
Of the remaining 5 units, two were removed from testing without failing after 300,000 cycles, and three were removed from testing after 600,000 cycles without failing. A. Compute the lower 80% confidence limit for reliability at 200,000 cycles. B. Compute the lower 80% confidence limit for the time to fail at 99% reliability.
Example 2One million units were introduced into the field 6 months ago. The number of failures per month are shown below.
What is the expected reliability of the population after 1 year in service?
Example 3Given the data in the file "Demo2.dat", A. Does the product represented in the data meet a requirement of 99% reliability with 80% confidence at time = 40? B. At what time does the product meet the requirement of 99% reliability with 80% confidence?
Example 4A new product is required to demonstrate 99% reliability at 1.5 million cycles with 80% confidence. Given a Weibull shape parameter of 2.8, how long must 8 units be tested to demonstrate the required reliability assuming no failures?
Example 5Nine samples were tested for 3 million cycles without failure, and 1 sample survived 2.84 million cycles before failing. Given a Weibull shape parameter of 3.8, what is the lower 95% confidence limit for reliability at 2 million cycles? What is the lower 95% confidence limit for the time to fail when the reliability is 99%? 