Answer to Question #44387 in Statistics and Probability for James

Question #44387

Engineers for a cell phone producer think that using Bluetooth decreases battery life. Average battery life is expected to be 23 hours. A sample of 20 phones was tested for battery life with Bluetooth enabled. The average for the sample was 22.5 hours with a standard deviation of 0.9 hours.

What is the null hypothesis?

What is the alternative hypothesis?

What is the test statistic t ?

What is the t value for a .05 one tailed critical (rejection) region?

Draw the rejection region.

Do you reject or fail to reject the null hypothesis? Show why you made your choice.

What is the approximate p value for the test?

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