$\"\"$

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The life of a certain brand of battery is normally distributed.

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The mean $\"\"$ and $\"\"$ .

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(a) The battery will last less than $\"\"$ .

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The probability of battery will last less than $\"\"$ is $\"\"$ .

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The formula for $\"\"$ -values is $\"\"$ .

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Substitute $\"\"$ , $\"\"$ and $\"\"$ .

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$\"\"$

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$\"\"$

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$\"\"$ .

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The table value of $\"\"$ is $\"\"$ or $\"\"$ .

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The probability of battery will last less than $\"\"$ is $\"\"$ .

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$\"\"$

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(b) The battery will last more than $\"\"$ .

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The probability of battery will last more than $\"\"$ is $\"\"$ .

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$\"\"$

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$\"\"$ .

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The table value of $\"\"$ is $\"\"$ or $\"\"$ .

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$\"\"$

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(c) The battery will last between $\"\"$ and $\"\"$ .

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The probability of battery will last between $\"\"$ and $\"\"$ is $\"\"$ .

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$\"\"$ .

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$\"\"$ .

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The $\"\"$ table value is $\"\"$ .

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The $\"\"$ table value is $\"\"$ .

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The probability of $\"\"$ is $\"\"$ or $\"\"$ .

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$\"\"$

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(a) $\"\"$ .

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(b) $\"\"$ .

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(c) $\"\"$ .