Consumer Reports tested 19 different brands and models of road, fitness, and comfort bikes. Road bikes are designed for long road trips; fitness bikes are designed for regular workouts or daily commuters; and comfort bikes are designed for leisure rides on typically flat roads. The data file Bikes show the type, weight (1b.), and price ($) for the 20 bicycles tested. a. At the 0.05 level of significance, test for autocorrelation in the data. Note: Entries in the table are the critical values for a one-tailed Durbin-Watson test for autocorrelation. For a two-tailed test, the level of significance is doubled. Significance Points of d,, and du: a = .05 Number of Independent Variables 2 3 4 5 du du du d du do 15 1.08 1.36 .95 1.54 .82 1.75 69 1.97 .56 2.21 20 1.20 1.41 1.10 1.54 1.00 1.68 90 1.83 .79 1.99 25 1.29 1.45 1.21 1.55 1.12 1.66 1.04 1.77 .95 1.89 30 1.35 1.49 1.28 1.57 1.21 1.65 1.14 1.74 1.07 1.83 40 1.44 1.54 1.39 1.60 1.34 1.66 1.29 1.72 1.23 50 1.79 1.50 1.59 1.46 1.63 1.42 1.67 1.38 1.72 1.34 70 1.77 1.58 1.64 1.55 1.67 1.52 1.70 1.49 1.74 1.46 100 1.65 1.77 1.69 1.63 1.72 1.61 1.74 1.59 1.76 1.57 1.78 *Interpolate linearly for intermediate n values