The pH of 20 randomly selected lakes is measured. Their average pH is 5.7. Part A. Historically...

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The pH of 20 randomly selected lakes is measured. Their averagepH is 5.7.
Part A. Historically the standard deviation in the pH values is0.9. Use this standard deviation for the following questions.
Part Ai. Build a 95% confidence interval for the population meanlake pH.
Part Aii. Build a 90% confidence interval for the population meanlake pH.
Part Aiii. Build an 80% confidence interval for the population meanlake pH.
Part Aiv. Compare the intervals you created in Ai, Aii and Aiii.What effect does changing the level of confidence have on theinterval?
Please solve only part B
Part B. For the 20 measured lakes the standard deviation in thepH values is 0.9. Use this standard deviation for the followingquestions.
Part Bi. Build a 95% confidence interval for the population meanlake pH.
Part Bii. Compare the confidence intervals in Bi and Ai. Whateffect does not knowing the value of ? have on the interval?
Part Biii. Test whether the population mean pH differs from 6.

Answer & Explanation Solved by verified expert

3.9 Ratings (715 Votes)

Part Bi Confidence interval for Population mean is given as below Confidence interval Xbar tSsqrtn From given data we have Xbar 57 S 09 n 20 df n 1 19 Confidence level 95 Critical t value 20930 by using ttable Confidence interval Xbar tSsqrtn Confidence interval 57 See Answer

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