Question

9. In a large discount store, the maintenance department has been instructed to replace all of the light bulbs at the same time. Past experience indicates that the lives of light bulbs are normally distributed with a mean life of 1250 hours and standard deviation of 70 hours. When should the lights be replaced so that no more than 11.5% burned out? Draw diagram for normal distribution, define the time of bulb replacement that separates the bottom 11.5% and circle one of the multiple choice answers. (6 points) C) 1166 D) 1180 B) 1146 A) 1334

Answer 1