Question 1145360
Go to a z-table and find the value that corresponds with a score of 0.04.  The closest z-score is -1.75.
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{{{(x - 9.9)/3.1 = -1.75}}}
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Cross-multiply:
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x - 9.9 = -5.425
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x = 4.475
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The 4% with the lowest lifespan will last less than 4.475 years.