Accelerated Life Test for Type-D Alkaline Batteries: Statistical Analysis and Findings

What is the Range of Failure Times for Type-D Alkaline Batteries in an Accelerated Life Test?

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An accelerated life test on a large number of type-D alkaline batteries revealed that the mean life for a particular use before they failed is 19.0 hours. The distribution of the lives approximated a normal distribution. The standard deviation of the distribution was 1.2 hours. About 95.44 percent of the batteries failed between what two values?

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A

9544/2 = 0.4772. For an area under the curve of 0.4772, the z value is (+/-)2. We know that z = (x-u)/sigma. Therefore, +/-2 = (x-19)/1.2. Rearranging we get x = u

+/- z*sigma. So x = 19 +/- 2*1.2 = 19+/-2.4. x is 16.6 and 21.4.

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