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.Calculate the appropriate test statistic to test the claim that the mean life of the batteries is more than 400 hours.
A)6.20
B)1.72
C)0.477
D)-6.20
E)-1.72

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The Answer of 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.Calculate the appropriate test statistic to test the claim that the mean life of the batteries is more than 400 hours.
A)6.20
B)1.72
C)0.477
D)-6.20
E)-1.72

The Quality Control Manager of a Major Cell Phone Provider