XYZ tires makes automobile tires that have a mean life of 80,000 miles with a standard deviation of 5,000 miles.
- What fraction of tires is expected to survive beyond 85,000 miles?
- what percentage of the tires has life between 76,000 and 83,000 miles?
- what percentage of the tires has a life between 73,000 and 88,000 miles?
- what fraction will survive fewer than 77,500 miles?
- what length of warranty is needed so that no more that 5.05 percent of the tires will be expected to fail during the warranty period?