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Standard deviation sample size for lifetime of washing machines

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The standard deviation of the lifetime of washing machines is estimated to be 800 hours. How large a sample must be taken in order to be 97% confident that the margin of error will not exceed 50 hours?

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This solution helps with a standard deviation problem.

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Sandhya Sharma, MSc
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  • BSc, Meerut University
  • MSc, Meerut University
  • MPhil, Institute of Advanced Studies
  • MSc, AIT
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