A major television manufacturer has determined that its 19-inch color TV picture tubes have a mean service life that can be modeled by a normal distribution with a mean of six years and a standard deviation of one-half years?
a. What probability can you assign to service lives of at least (1) Five years? (2) Six years? (3) Seven and one-half years?
b. If the manufacturer offeres service contracts of four years on these picture tubes, what percentage can be expected to fail from wear-out during the service period?