Answer: 68% of light bulbs last between 1765 hours and 1835 hours.
Step-by-step explanation:
The empirical rule states that for a normal distribution, nearly all of the data will fall within three standard deviations of the mean . The empirical rule is further illustrated below
68% of data falls within the first standard deviation from the mean.
95% fall within two standard deviations.
99.7% fall within three standard deviations.
From the information given, the mean is 1800 hours and the standard deviation is 35 hours.
1 standard deviation = 1 × 35 = 35
1800 - 35 = 1765 hours
1800 + 35 = 1835 hours
Therefore, 68% of light bulbs last between 1765 hours and 1835 hours.
