In the light bulb industry, the Average Rated Life (ARL) refers to the lifespan of a bulb. A certain light
bulb is tested and has a mean ARL of 1,250 hours and a standard deviation of 125 hours. The shape
of the distribution is approximately normal. What would we expect the lifespan to be for 99.7% of this
light bulb?
For this light bulb, we would expect 99.7% of bulbs to last between
hours.
hours and
875
1000
1125
1250
1375
1500
1625