To see whether a widely used food preservative contributes to the hyperactivity of preschool children, a dietitian chose a random sample of 10 four-year-olds known to be fairly hyperactive from various nursery schools and observed their behavior 45 minutes after they had eaten measured amounts of food containing the preservative. here variables were x, the amount of food consumed containing preservative (in grams) and y, a subjective rating of hyperactivity (on a scale from 1 to 20). the least-squares equation is y = 1.5 + 0.16x. if a child's hyperactivity rating is predicted to be 18, how many grams of food containing preservatives did he consume?