1) The component designer for a major off the road vehicle manufacturer estimates that she can (a) increase the average time between failures of a part by 5%, or (b) reduce the average repair time by 10%. Currently, the average time between failures is 100 hours and the average repair time is 4 hours. Which option would be result in higher Availability? Show all calculations.
2) The service life of automobile tires is modeled by a normal curve; the Mean Time Between Failures (MTBF) is 20,000 miles and the standard deviation is 800 miles. Use Table B in Appendix B (page 868 and 869) to solve these problems (text book: operation Management, 12 ed: by william J.)
a) Determine the probability that a tire will fail before 22,000 miles.
b) Determine the probability that a tire will last at least 19,000 miles
c) The manufacturer wishes to provide a warranty on which he will be obligated to make a replacement of only 1% of the tires sold. For how many miles should he warrant the tires?