Assignment Writing #1
By
Robbie Plagens
For writing assignment number 1, we were told to solve an equation that had to do
with a rectangles rate of change. The rectangle represented a portion of Butler county
that was infected by an insect called the ash borer. The portion in 2005 was 2 miles in
height and 3 miles in width.
a) In 2007, 1.17 square miles of this insect spread because the height of the portion was
spreading south at a rate of .08 miles/year, so multiplying that by two (added to 2005 to
get 2007) results in .16 and the width was spreading at a rate of .16 miles/year so I did the
same thing and got miles .32 spread to the east in two years. To get how many square
miles were added to the original, I added these values to the originial height and width
and multiply those numbers to get 7.17 square miles. But to get just how many square
miles were added on I subtracted 6 (3x2), to result in 1.17 square miles.
b) To find out how fast the insect was spreading in 2012, I multiplied the rates of change
by 7. So the equation looks like this.
A(2012)=[2(.08x7)]x[3(.16x7)]=3.8 square miles of insect spreading.
Then I divided that answer by 7
3.8 square miles
7 years
That answer comes out to .5 square miles per year.