Wear-out of used display panels. Refer to Exercise 4.126 (p. 270) and the study of the wear-out failure time of used colored display panels purchased by an outlet store. Recall that prior to acquisition, the panels had been used for about one-third of their expected lifetimes. The failure times (in years) for a sample of 50 used panels are reproduced in the table. An SPSS printout of the analysis is shown below.

a. Locate a 95% confidence interval for the true mean failure time of used colored display panels on the printout.

b. Give a practical interpretation of the interval, part a.

c. In the repeated sampling of the population of used colored display panels, where a 95% confidence interval for the mean failure time is computed for each sample, what proportion of all the confidence intervals generated will capture the true mean failure time?

Short Answer

Expert verified
  1. (1.6776,2.1924)


  2. We can say that the mean failure time lies between (1.6776,2.1924) 95% time
  3. 0.95

Step by step solution

01

(a) Calculating Confidence Interval

From the given output, 95% confidence interval for the true mean failure time of used colored display panels: (1.6776,2.1924).

02

(b) Practical Interpretation

We are 95% confident that the true mean failure time of used colored display time of used colored display panels lies within (1.6776,2.1924)

03

(c) Calculating proportions of Confidence Intervals

Suppose we were to take many different samples and compute a 95% confidence interval for each sample. In that case, the proportion of all the confidence intervals generated will capture the true mean failure time is approximately 0.95.

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