Twenty units were placed on stress. Readouts were done at the end of each week at 168, 332, 504, 672, 840, and 1008 hours. The failure counts observed at the readouts were 0, 4, 5, 3, 2, and 2, respectively. At the end of weeks 2, 3, 4, and 5, one randomly chosen surviving unit was removed for failure analysis. Using the Kaplan-Meier PLE for interval data, estimate the CDF at the observed failure times. Estimate the standard error of the CDF estimate using Greenwood's formula. Provide 90% pointwise confidence intervals at each readout using the normal approximation. Redo the confidence interval estimates by applying the log and logistic transformations.