An estimated regression equation y = 3.5 0.25 x1 -0.3 x2 has standard deviations of 0.02 and 0.25 of x1 and x2 respectively. Which variables are statistically significant to explain y? An estimated regression equation y = 3.5 0.25 x1 -0.3 x2 has standard deviations of 0.02 and 0.25 of x1 and x2 respectively. Which variables are statistically significant to explain y? neither x1 nor x2 only x2 Only x1 both x1 and x2