01 (a) The cumulative distribution function of failure of an electronic device is 1 7+1 Time to failure, t, is measured in years. (1) Determine expressions for the probability density function of t. failure rate and the mean time to failure (MTTF) over T, (> 1) years of operation. (ii) (6 marks) What is MTTF over the same period of time with annual preventive maintenance, which restores the device to "as good as new condition"? Does it make sense to carry out preventive maintenance of this device? Explain your answer. (4 marks) (b) An electronic component is sold with a three-year warranty under condition that no more than 3% of these components should be returned under the warranty. What is the tolerable failure rate of the component? Assume the constant failure rate. (5 marks) (c) The life of a product is normally distributed with MTTF of five years and standard deviation of 1.5 years. What is the design life (in years) of the product if the required reliability over the design life is 90%? (5 marks) (d) The failure rate of a generator (per million hours) is given by the following expression 2(r)=20+0.5r (pmh) Determine the interval between consecutive planned preventive maintenance of the generator if the required reliability at the end of the interval is 95% and the maintenance restores the generator to "as good as new condition".