Answer
a. $(2005,2006)$, $(2007,2008)$, and $(2009,2011)$,
b. $(2006,2007)$ and $(2008,2009)$,
c. $4$
d. $5$
e. positive
f. $3.20$ dollars, in $2011$
g. $1.80$ dollars, in $2009$
Work Step by Step
Based on the given graph, we have:
a. increasing over years $(2005,2006)$, $(2007,2008)$, and $(2009,2011)$,
b. decreasing over years $(2006,2007)$ and $(2008,2009)$,
c. there are $4$ turning points
d. the degree of the polynomial function should be $5$
e. the leading coefficient should be positive as the end behavior is $x\to\infty, y\to\infty$
f. the maximum is about $3.20$ dollars, which happens in 2011
g. the minimum is about $1.80$ dollars, which happens in 2009
