The data of Table 7.15 show the sugar content of a fruit (Sugar) for different numbers of days after picking (Days). 

(a) Obtain the estimated regression line to predict sugar content based on the number of days after picking. 

(b) Calculate and plot the residuals against days. Do the residuals suggest a fault in the model?

Table 7.15 Data for Exercise 2 Days Sugar 7.9 12.0 9.5 4 11.3 11.8 11.3 4.2 8. 0.4