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Problem 2

 

9.2 Z-Test to Compare Two Population Means: Independent Samples

Concept
Problem 1
Problem 3
Graphing Calculator Example
Now You Try It!

Which batteries last longer?  A randomly selected sample of 92 Duralife AA batteries had an average lifespan of 46.2hrs with a standard deviation of 2.67 hrs.  A randomly selected sample of 91 Energy AA batteries had an average lifespan of 42.9hrs with a standard deviation of 3.17 hrs.    Use a 5% significance level to test the claim that Duralife batteries last longer on average.

 

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