$\"\"$

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The sales of a seasonal product model is $\"\"$ , where $\"\"$ is the time in months.

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(a) Find the average sales for first quarter $\"\"$ .

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Definition of the Average Value of a Function on an Interval:

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If $\"\"$ is integrable on the closed interval $\"\"$ , then the average value of $\"\"$ on the interval is $\"\"$ .

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In this case $\"\"$ and $\"\"$ .

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The sales of a seasonal product model is $\"\"$ .

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The average value of first quarter is $\"\"$ .

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$\"\"$ $\"\"$

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$\"\"$

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$\"\"$

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$\"\"$

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$\"\"$

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$\"\"$

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$\"\"$

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$\"\"$

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$\"\"$

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$\"\"$

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$\"\"$

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$\"\"$ .

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The average sales for first quarter is $\"\"$ .

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$\"\"$

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(b) Find the average sales for first quarter $\"\"$ .

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In this case $\"\"$ and $\"\"$ .

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The sales of a seasonal product model is $\"\"$ .

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The average value of second quarter is $\"\"$ .

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$\"\"$ $\"\"$

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$\"\"$

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$\"\"$

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$\"\"$

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$\"\"$

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$\"\"$

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$\"\"$

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$\"\"$

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$\"\"$

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$\"\"$

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$\"\"$

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$\"\"$ .

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The average sales for second quarter is $\"\"$ .

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$\"\"$

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(c) Find the average sales for entire year $\"\"$ .

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In this case $\"\"$ and $\"\"$ .

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The sales of a seasonal product model is $\"\"$ .

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The average value of entire year is,

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$\"\"$

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$\"\"$

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$\"\"$

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$\"\"$

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$\"\"$

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$\"\"$

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$\"\"$

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$\"\"$

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$\"\"$

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$\"\"$

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$\"\"$

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$\"\"$ .

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The average sales for entire year is $\"\"$ .

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$\"\"$

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(a) The average sales for first quarter is $\"\"$ .

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(b) The average sales for second quarter is $\"\"$ .

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(c) The average sales for entire year is $\"\"$ .