A manufacturer of automobile batteries claims that the average length of life for its grade A battery is 60 months. However, the guarantee on this brand is for only 36 months. Suppose the standard deviation of the life length is known to be 10 months, and the frequency distribution of the lifelength data is known to be mound-shaped. a. Approximately what percentage of the manufacturer's grade A batteries will last more than 50 months, assuming the manufacturer's claim is true? b. Approximately what percentage of the manufacturer's batteries will last less than 40 months, assuming the manufacturer's claim is true? c. Suppose your battery lasts 37 months. What could you infer about the manufacturer's claim?
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