How many light bulbs must a company test to determine the mean number of hours that...
How many light bulbs must a company test to determine the mean number of hours that they will last? The company wants to be 90% confident that their mean is within 40 hours of the population mean (Assume that the population standard deviation is 150).
Homework Answers
| for90% CI crtiical Z = | 1.645 | |
| standard deviation σ= | 150 | |
| margin of error E = | 40 | |
| required sample size n=(zσ/E)2 = | 39 |
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How many light bulbs must a company test to determine the mean
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