The lifetime of a color television picture tube is normally distributed with a mean of 7.8 years and a standard deviation of 3 years.
a. What is the probability that a picture tube will last more than ten years?
b. If the firm guarantees the picture tube for 2 years, what percentage of the television sets sold will have to be replaced because of the picture tube failing?
c.How long should the warranty period be (in years) if they want to replace only 1% of the television picture tubes?