$\"\"$

\

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

\

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

\

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

\

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

\

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

\

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

\

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

\

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

\

$\"\"$

\

$\"\"$

\

$\"\"$

\

$\"\"$

\

$\"\"$

\

$\"\"$

\

$\"\"$

\

$\"\"$

\

$\"\"$

\

$\"\"$

\

$\"\"$ .

\

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

\

$\"\"$

\

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

\

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

\

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

\

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

\

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

\

$\"\"$

\

$\"\"$

\

$\"\"$

\

$\"\"$

\

$\"\"$

\

$\"\"$

\

$\"\"$

\

$\"\"$

\

$\"\"$

\

$\"\"$

\

$\"\"$ .

\

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

\

$\"\"$

\

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

\

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

\

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

\

The average value of entire year is,

\

$\"\"$

\

$\"\"$

\

$\"\"$

\

$\"\"$

\

$\"\"$

\

$\"\"$

\

$\"\"$

\

$\"\"$

\

$\"\"$

\

$\"\"$

\

$\"\"$

\

$\"\"$ .

\

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

\

$\"\"$

\

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

\

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

\

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