R commands and output: ## Evaluate a lognormal CDF at time T. T = 100000 T50 = 507383 sigma = 0.74 y = plnorm(T/T50, sdlog=sigma) y > [1] 0.01409169 ## Evaluate a use CDF or failure rate for a T-hour stress test ## for a lognormal distribution. ## T = length of test ## p = proportion of failures ## sigma = shape parameter ## A = acceleration factor T50STRESS = T*qlnorm(p, sdlog=sigma) CDF = plnorm((100000/(A*T50STRESS)), sdlog=sigma) ## Evaluate a use CDF or failure rate for a T-hour stress test ## for a Weibull distribution. ## gamma = shape parameter ASTRESS = T*qweibull(p, shape=gamma) CDF = pweibull((100000/(A*ASTRESS)), gamma)