1. A researcher obtained n=25 observations [xir'i] and now wants to use the model {Yi Y] = a pa or]. + E for r=l, 2, , 25 to describe the data. The researcher wants to estimate B by using the principle of least squares but does not know Calculus. So, the researcher plans to give the equation for the Sum of Squares that needs to be minimized to a mathematician for deriving the estimator of B. Write the equation for the Sum of Squares that the researcher needs to give to the mathematician for minimization. 2. Why did we need to obtain an estimate of oz