3. The lifetime of an LED in a certain application is normally distributed with a mean µ =25,000 hours and a standard deviation o = 1500 hours. a. What is the probability that a light bulb will last more than 24,000 hours? b. Find the 75th percentile of lifetimes. c. A particular bulb lasts 27,500 hours. What percentile is its lifetime in? d. What is the probability that the lifetime of an LED is between 20,000 and 30,000 hours?