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 year. What service period would achieve an expected wear-out rate of Use Table A and Table B. a. 2 percent? (Round your answer to 2 decimal places.) Service period yr b. 5 percent? (Round your answer to 2 decimal places.)