An article in Microelectronics Reliability presented an example of electronic prognosis. The objective was to detect faults to decrease the system downtime and the number of unplanned repairs in high-reliability systems. Previous measurements of the power supply indicated that the signal is normally distributed with a mean of 1.5 V and a standard deviation of 0.02 V.
(a) Suppose that lower and upper limits of the predetermined specifications are 1.45 V and 1.55 V, respectively. What is the probability that a signal is within these specifications?
(b) What is the signal value that is exceeded with 95% probability?
(c) What is the probability that a signal value exceeds the mean by two or more standard deviations?