The data in the accompanying table are from the paper Six Minute Walk Test in Children and Adolescents(The Journal of Pediatrics [ 2007]: 395 399).

The data in the accompanying table are 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 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.
c. Compute the five residuals and construct a residual plot. Are there any unusual features in the residual plot?

Representative Age Median Stx-minute Age Group 3-5 6-8 9-11 12-15 16-18 (midpoint of age group) 4.0 7.0 10.0 13.5 17.0 Walk Distance (meters) 544.3 584.0 667.3 701.1 727.6