Two observations on Y were obtained at each of three X levels, namely, at X = 5, X = 10, and X = 15.

Show that the least squares regression line fitted to the three points (5, Y1(bar)), (10,Y2(bar)), and (15, Y3(bar)), where Y1(bar), Y2(bar), and Y3(bar) denote the means of the Y observations at the three X levels, is identical to the least squares regression line fitted to the original six cases.

1.39. Two observations on I' were obtained at each of three X levels, namely, at X = 5. X =10, and X = 15. a. Show that the least squares regression line fitted to the three points (5, Y,). (10. Y,), and (15, Y:). where Y, Yz. and I denote the means of the Y observations at the three X levels, is identical to the least squares regression line fitted to the original six cases