Question: PRODUCT RELIABILITY A Christmas tree light has an expected life of 200 hr and a standard deviation of 2 hr.
a. Find a bound on the probability that one of these Christmas tree lights will last between 190 hr and 210 hr.
b. Suppose 150,000 of these Christmas tree lights are used by a large city as part of its Christmas decorations. Estimate the number of lights that are likely to require replacement between 180 hr and 220 hr of use.