11.50 The amounts of solids removed from a particu- lar material when exposed to drying periods of different lengths are as shown. x (hours) y (grams) 4.4 13.1 14.2 4.5 9.0 11.5 4.8 10.4 11.5 5.5 13.8 14.8 5.7 12.7 15.1 5.9 9.9 12.7 6.3 13.8 16.5 6.9 16.4 15.7 7.5 17.6 16.9 7.8 18.3 17.2 (a) Estimate the linear regression line. (b) Test at the 0.05 level of significance whether the linear model is adequate.