What is a hazard rate and how does it differ for exponential versus Weibull distributions?

• A. The hazard rate is the instantaneous failure rate at time t; for exponential it is constant, for Weibull it depends on t: h(t) = (β/η)(t/η)^{β-1}.
• B. The hazard rate is the average failure rate over life; exponential increases with time; Weibull decreases.
• C. The hazard rate is the failure probability in the next second; Exponential decreases; Weibull constant.
• D. The hazard rate is the rate of repairs; Exponential constant; Weibull zero.

Answer: (A)