$\"\"$

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The survey conducted for $\"\"$ .

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According to survey the average noise is $\"\"$ .

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The standard deviation is $\"\"$ .

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(a) A normal conversation is held at about $\"\"$ .

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Find the number of hours during the study that the noise level was this low.

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$\"\"$ is $\"\"$ from the mean.

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Because $\"\"$ of the data values with in two standard deviations from the mean, each tail represents $\"\"$ of the data.

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The area to right of $\"\"$ is $\"\"$ .

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$\"\"$ .

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The number of hours during the study that the noise level was this low is $\"\"$ .

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$\"\"$

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(b)

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Find the percent of the study during which the noise was between $\"\"$ and $\"\"$ .

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The percent of the study during which the noise was between $\"\"$ and $\"\"$ is represented by $\"\"$ and $\"\"$ .

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From emperical rule:

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The total area under the curve between $\"\"$ to $\"\"$ is $\"\"$

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The percent of the study during which the noise was between $\"\"$ and $\"\"$ is $\"\"$ .

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$\"\"$

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(a) The number of hours during the study that the noise level was this low is $\"\"$ .

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(b) The percent of the study during which the noise was between $\"\"$ and $\"\"$ is $\"\"$ .