Question

A bulb company manufactures a new kind of light bulb based on the latest LED technology. The (population) mean life of a bulb is 7.0 years with a population standard deviation of 1.4 years. The mean life of a bulb is normally distributed. a. What proportion of bulbs will last more than 9.5 years? (5 points) b. What proportion of bulbs will last less than 4.0 years? (5 points) c. What proportion of bulbs will last between 8.0 and 9.0 years? (5 points) d. Calculate the 90th percentile for a bulb.

Answer 1

c. The proportion of bulbs will last between 8.0 and 9.0 years.