5.21) ▼ The accompanying data on x head circumfer- ence z score (a comparison score with peers of the same age-a positive score suggests a larger size than for peers) at age 6 to 14 months and y =...

Extracted text: 5.21) ▼ The accompanying data on x head circumfer- ence z score (a comparison score with peers of the same age-a positive score suggests a larger size than for peers) at age 6 to 14 months and y = volume of cerebral grey matter (in ml) at age 2 to 5 years were read from a graph in the article described in the chapter introduction (Jour- nal of the American Medical Association [2003]). Head Circumfer- Cerebral Grey ence z Scores at Matter (ml) 2–5 yr 6-14 Months 680 -.75 690 1.2 700 -.3 720 .25 740 .3 740 1.5 750 1.1 750 2.0 760 1.1 780 1.1 790 2.0 810 2.1 815 2.8 820 2.2 825 .9 835 2.35 840 2.3 845 2.2 a. Construct a scatterplot for these data. b. What is the value of the correlation coefficient? c. Find the equation of the least-squares line. by using Sor mulas.