Each day a quality engineer selects a random sample of 50 power supplies from the day’s production, measures their output voltages, and computes a 90% confidence interval for the mean output voltage of all the power supplies manufactured that day. What is the probability that more than 15 of the confidence intervals constructed in the next 200 days will fail to cover the true mean?

Solution:

Step 1 of 3:

A quality engineer selects a random sample of 50 power suppliers from the day’s production, and computes a 90% CI for the mean output voltage of all the power suppliers manufactured at that day.

We have to find the probability that more than 15 of the CI constructed in the next 200 days will fail to cover the true mean.