In a regression analysis involving 27 observations, the following estimated regression equation was developed: y= 25.2 + 5.5x1

For this estimated regression equation SST= 1550 and SSE= 520.

At a=.05 test whether x1 is significant.

Suppose that variables x2 and x3 are added to the model and the following regression equation is obtained: y= 16.3 + 2.3x1 +12.1x2 - 5.8x3.

For this estimated regression equation SST = 1550 and SSE = 100.

Use an F test and a .05 significance to determine whether x2 and x3 contribute significantly to the model.