Abstract: A test of hypothesis for population percentiles and percentage is presented in this paper. The method is applicable to the three-parameter Weibull, the normal, the extreme value, the gamma and a host of other continuous distributions. And it is simple and convenient for application in engineering. The test for percentiles and percentage of the three-parameter Weibull and the extreme value distribution, which have become prominent in engineering design, is discussed at some length. Many results of fatigue experiments have been well treated by this method.

Key words: test of hypothesis, reliability, three-parameter Weibull distribution, cxtreme distribution