1. Consider the Simple Linear Regression (SLR) model 312' = 160 +161$i+5n where the as have zero mean, variance 0'2 and are uncorrelated. Sometimes it is convenient to write the SLR model in the following way: \"yr =150+51$i+r=50+5158r51173+515'+r =(50+511E)+51($ii')+8i=a+51(:c1T3)+5i 'v" 22C! where we have dened a := ,80 + [31:73, with :T: = (2:1 LBJ. (a) What is the meaning of the parameter a? (b) Derive the leastsquares estimators for a and ,81