An energy-saver light bulb is advertised as having an average life of 10,000 hours with a standard deviation of T00 hours. The factory produces 100,000 bulbs per day. If the life spans are normally distributed: Below how many hours will the weakest 10% of bulbs last? Above how many hours will the strongest 5% of bulbs last? Between how many hours will the central 80% of bulbs last