Math

If light bulbs have lives that are normally distributed with a mean of 2500 hours and a standard deviation of 500 hours, use the 68-95-99.7 rule to approximate the percentage of light bulbs having a life between 2000 hours and 3500 hours?
A. About 13.5%
B. About 50%
C. About 68%
D. About 81.5%

answer :C

asked by angela
  1. agree with second answer.

    posted by PsyDAG

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