Thetablebelowshowsthesalesamountandtheamountspentonadvertisingofacompanyduring2005-2013years.Weconsideredyear2005asabaseyear:wecantransformtheyearsast=x-2004.

t(year) 1 2 34 5 6 7 8 9

y(sales:millioneuro) 651 7628561063 1190 1298 1421 1440 1518

x(advertising:millioneuro) 23 263034 43 48 52 57 58

a.Whatproportionofobservedvariationinsalescanbeattributedtotheapproximatelinearrelationshipbetweenthetwovariables?

b.Computetheestimatedstandarddeviation.

c.Calculateaconfidenceintervalusingconfidencelevel95%fortheexpectedchangeinsalesassociatedwitha1unitincreaseinadvertisement.

d.Calculateaconfidenceintervalwithaconfidencelevelof95%forthetrueaveragesaleswhenadvertisingis45.

e.Calculateapredictionintervalwithapredictionlevelof95%forthesalesofasinglecomponentwhenadvertisingis45