Answer:
Explanation:
The empirical rule states that for a normal distribution, approximately 68% of the data falls within one standard deviation of the mean. Therefore, to find the interval of hours that represents the lifespan of the middle 68% of light bulbs, we need to find the interval that is one standard deviation away from the mean in either direction.
Since the mean is 1400 hours and the standard deviation is 50 hours, we can use the following formula to find the interval:
(mean - standard deviation, mean + standard deviation)
Plugging in the values, we get:
(1400 - 50, 1400 + 50)
Simplifying, we get:
(1350, 1450)
Therefore, the interval of hours that represents the lifespan of the middle 68% of light bulbs is from 1350 hours to 1450 hours.