Chapter 17: Data on steam consumption, temperature and operating days.

Col 1: Y (pounds of steam used per month)
Col 2: X1 (average atmospheric temperature in degrees Fahrenheit)
Col 3: X2 (number of operating days per month)

       10.98 35.2 20
       11.13 29.7 20
       12.51 30.8 23
         8.40 58.8 20
         9.27 61.4 21
         8.73 71.3 22
         6.36 74.4 11
         8.50 76.7 23
         7.82 70.7 21
         9.14 57.5 20
         8.24 46.4 20
        12.19 28.9 21
        11.88 28.1 21
         9.57 39.1 19
        10.94 46.8 23
         9.58 48.5 20
        10.09 59.3 22
         8.11 70.0 22
         6.83 70.0 11
         8.88 74.5 23
         7.68 72.1 20
         8.47 58.1 21
         8.86 44.6 20
        10.36 33.4 20
        11.08 28.6 22