An experiment was conducted to evaluate the relationship between days of drilling (X) and total dry matter (Y) in t/ha for autumn-sown winter barley Table 1: Vegetative development of autumn-sown winter barley No. Days of Total dry drilling matter (t/ha) 100 0.2 2 130 0.4 3 150 0.8 4 198 1.9 5 204 2.2 6 214 3.2 7 220 3.9 8 229 6.5 9 234 8.5 10 241 10.1 11 246 12.2 (a) Create a scatter plot for the data. What can you infer from this scatter plot? (2) (b) Do a regression analysis and test for the slope. You must include the hypothesis and the result of the analysis. What is your conclusion? (4) (c) Write down the linear regression equation. (2) (d) Predict the total dry matter for 80 days of drilling. (2)