Question 275990
You are responsible for reliability of the electronic product that your company produces. 

You decide to measure the time between equipment malfunctions over a one-year period. Over that time you measured 40 electronic products. You made 850 observations with a mean time between equipment failures of 550.35 hours, and a sample standard deviation of 207 hours. 

Your company supplies the electronic product to another company as a component to their product. You guarantee an average time between malfunctions of 600 or more hours. 

Calculate a 99% confidence interval estimate for the mean time between malfunctions for all electronics of this type then interpret the results to assess whether your company will have a problem with this guarantee. Explain your reasoning?
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sample mean = 550.35
standard error = E = invNorm(0.995)*207/sqrt(850) = 18.29
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99% CI: 550.35-18.29 < u < 550.35+18.29
99% CI: 532.06 < u < 568.64
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For your component your guarantee it too high.
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Cheers,
Stan H.