Consider the following times to failure of a sample of five items: 

 

a) Plot the data using Weibull probability paper. Do you consider it appropriate to continue to fit a Weibull distribution to this data? 

b) Estimate the Weibull parameters (β, η and γ) from your chart and give an interpretation of their values. 

c) Use your chart to estimate the following: 

i) The reliability of the item after 1200 hours. 

ii) The time at which the item is 70% reliable. 

d) For each of the following cases, describe the pattern that is likely to be seen in a Weibull plot and describe how you would continue your analysis after the initial plot. i) multiple failure modes exist ii) there exists an amount of failure free time.

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Failure Number (1) 1 2 3 4 5 Ranked Hours at Failure 450 770 1150 1400 2000 Median Rank 0.13 0.31 0.5 0.69 0.87 Failure Number (1) 1 2 3 4 5 Ranked Hours at Failure 450 770 1150 1400 2000 Median Rank 0.13 0.31 0.5 0.69 0.87