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Confidence Interval & Sample Size Calculated Step by Step

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1.
If X bar = 85, σ = 8, and n = 64, construct a 95% confidence interval estimate for the population mean, µ.
Show work! That is draw the a) normal curve, b) put in the given information(mean and standard deviation), c) identify the area to be solved, d) show the Z conversion of the X values, e) use the Standardized normal Table, f) give interpretation of your results. For help, see steps in the model answer in the previous week.

2.
If a quality control manager wants to estimate, with 95% confidence, the mean life of light bulbs to within ±20 hours and also assumes that the population standard deviation is 100 hours, how many light bulbs need to be selected?
Show work! See the steps above (a) through (f)

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Solution Summary

The solution provides step by step method for the calculation of confidence interval and sample size. Formula for the calculation and Interpretations of the results are also included. Interactive excel sheet is included.

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1. If X bar = 85, σ = 8, and n = 64, construct a 95% confidence interval estimate for the population mean, µ.
Show work! That is draw the a) normal curve, b) put in the given information(mean and standard deviation), c) identify the area to be solved, d) show the Z conversion of the X values, e) use the Standardized normal Table, f) give interpretation of your results. For help, see steps in the ...

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