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 5.8 years and a standard deviation of .6 year. Use Table A and Table B.
What probability can you assign to service lives of at least: (1) Four and one-half years? (2) Five years? (3) Six years? (Round "probability" answers to 4 decimal places and "z" answers to 2 decimal places. Negative amounts should be indicated by a minus sign. Leave no cells blank - be certain to enter "0" wherever required.)
If the manufacturer offers service contracts of Four years on these picture tubes, what percentage can be expected to fail from wear-out during the service period? (Round your answers to 2 decimal places. Negative amounts should be indicated by a minus sign. Leave no cells blank - be certain to enter "0" wherever required.)