Use the frequency distribution to find the mean and the sample standard deviation. Does the data form a normal distribution? Remember: if the data fall within 2% of the empirical rule of 68%, 95%, and 99.7% for one, two, or three standard deviations, respectively, they form a normal distribution. 
Life of bulb (hours)       Frequencyf0 - 999.5                     103999.5 - 1,999.5               4761,999.5 - 2,999.5             2,0622,999.5 - 3,999.5             4,1293,999.5 - 4,999.5             2,4604,999.5 - 5,999.5             4215,999.5 - 6,999.5             146   

A. The mean is 3,546 hours. The sample standard deviation is 1,018 hours. The data forms a normal distribution.
B. The mean is 3,523 hours. The sample standard deviation is 1,017 hours. The data forms a normal distribution.
C. The mean is 3,546 hours. The sample standard deviation is 1,018 hours. The data doesn't form a normal distribution.
D. The mean is 3,542 hours. The sample standard deviation is 1,027 hours. The data forms a normal distribution.
E. The mean is 3,523 hours. The sample standard deviation is 1,017 hours. The data doesn't form a normal distribution.


Answer: D

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