SOLUTION: The lifetimes of projector bulbs of a particular type are normally distributed with a mean of 470 hours and a standard deviation of 15 hours. What percentage of the bulbs has lifet

Algebra ->  Probability-and-statistics -> SOLUTION: The lifetimes of projector bulbs of a particular type are normally distributed with a mean of 470 hours and a standard deviation of 15 hours. What percentage of the bulbs has lifet      Log On


   



Question 935469: The lifetimes of projector bulbs of a particular type are normally distributed with a mean of 470 hours and a standard deviation of 15 hours. What percentage of the bulbs has lifetimes that lie within 2 standard deviations of the mean on either side?
Apply the 68-95-99.7 rule to this question.

Answer by TimothyLamb(4379) About Me  (Show Source):
You can put this solution on YOUR website!
the 68-95-99.7 rule:
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in a normal distribution, 68.27% of the values lie within one standard deviation of the mean, 95.45% of the values lie within two standard deviations of the mean, and 99.73% of the values lie within three standard deviations of the mean.
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answer:
95.45%
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