The quality control manager of a major cell phone provider is concerned about the life of the cell phone batteries they use. He took a sample of 13 batteries from a recent shipment and used them continuously until they failed to work. The manager measured the number of hours the batteries lasted and found the mean to be 550.4 with a standard deviation of 315.3.
-The null and alternative hypotheses to provide evidence that the mean life of the batteries is more than 400 hours is _____.

Question

Quizplus · Accepted Answer

The null hypothesis (H0) is typically a statement of no effect or no difference, and it often includes an equality (e.g., =). The alternative hypothesis (Ha) is what the researcher wants to prove, and it includes an inequality (e.g., ≠, <, >). Since the manager wants to provide evidence that the mean life of the batteries is more than 400 hours, the null hypothesis should state the mean life is equal to or less than 400 hours, and the alternative hypothesis should state the mean life is greater than 400 hours. Therefore, the correct hypotheses are H0: μ ≤ 400 vs. Ha: μ > 400.

The Quality Control Manager of a Major Cell Phone Provider