Question 316684
Find the yearly cost by adding quarter by quarter for each of the 5 years.
(1,32.1)
(2,37.3)
(3,39.6)
(4,41.1)
(5,45.5)
Fit this with a linear model,
{{{xave=3}}}
{{{yave=39.1}}}
{{{ SSXY=30.6}}}
{{{ SSXX=10}}}
{{{ SSYY=97.448}}}
{{{ b=SSXY/SSXX=3.06}}}
{{{ b'=SSXY/SSYY=0.314}}}
{{{ r^2=b*b'=0.961}}}
{{{ a=yave-b*xave=29.94}}}
{{{ y=3.06x+29.94 }}}
.
.
.
where x-Year, y-Advertising Cost in millions
You can then use this model to forecast future costs. 
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.
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{{{drawing(300,300,-2,10,-2,50,grid(1),
circle(1,32.1,.3),
circle(2,37.3,.3),
circle(3,39.6,.3),
circle(4,41.1,.3),
circle(5,45.5,.3),
graph(300,300,-2,10,-2,50,3.06x+29.94))}}}