Lengths of pencils. The length measurements of 20 consecutively produced pencils are recorded in the table (top, right).

a. Construct a time series plot. Be sure to connect the plotted points and add a centerline.

b. Which type of variation pattern in Figure13.6 best describes the pattern shown in your plot? Order of Production Length (inches) Order of Production Length (inches) 1 7.47 11 7.57 2 7.48 12 7.56 3 7.51 13 7.55 4 7.49 14 7.58 5 7.50 15 7.56 6 7.51 16 7.59 7 7.48 17 7.57 8 7.49 18 7.55 9 7.48 19 7.56 10 7.50 20 7.58