The data in the accompanying table is from the paper Six-Minute Walk Test in Children and Adolescents (The Journal of Pediatrics [2007]: 395399). Two hundred

The data in the accompanying table is from the paper €œSix-Minute Walk Test in Children and Adolescents€ (The Journal of Pediatrics [2007]: 395€“399). Two hundred and eighty boys completed a test that measures the distance that the subject can walk on a flat, hard surface in 6 minutes. For each age group shown in the table, the median distance walked by the boys in that age group is also given.

a. With x = representative age and y = median distance walked in 6 minutes, construct a scatterplot. Does the pattern in the scatterplot look linear?
b. Find the equation of the least-squares regression line that describes the relationship between median distance walked in 6 minutes and representative age.
c. Compute the five residuals and construct a residual plot. Are there any unusual features in the plot?

Representative Age (Midpoint of Age Group) Median Six-minute Walk Distance (meters) Age Group 3-5 6-8 9-11 12-15 16-18 10 13.5 17 544.3 584.0 667.3 701.1 727.6