Estimating reliability or failure using the Quick Calculation Pad

[Fudjie]

What do the upper and lower limits actually mean? Do they indicate, at some confidence level, the worst and best case of a reliability estimate of the population?
If this is the case, I am a bit confused because I thought the limits are always changing everytime a new sample is tested.
Thanks for any help

[RS Support]

See discussion at http://www.weibull.com/LifeDataWeb/confidence_bounds.htm