Question: The Karine Light Company manufactures inexpensive light-emitting dfode (LED) bulbs whose estimated lifetime is normally distributed with a mean of 9 200 hours and a standard deviation of 600 hours. Assume that they are lighted continuously:
(a) Calculate the probability that the LED will fail within one year.
(b) Calculate the probability that the LED will still be operating 400 days after installation.
(c) Out of 100 LEDs, about how many will have lifetimes between 8 500 and 10 200 hours?