The cetane number is a critical property in specifying the ignition quality of a fuel used in a diesel engine. Determining this number for a biodiesel fuel is expensive and time consuming. The article "Relating the Cetane Number of Biodiesel Fuels to Their Fatty Acid Composition: A Critical Study" (J. of Automobile Engr., 2009: 565-583) in- cluded the following data on r = iodine value (g) and y = cetane number for a sample of 14 biofuels. The iodine value is the amount of iodine necessary to saturate a sample of 100 g of oil. 132.0 129.0 120.0 113.2 105.0 92.0 84.0 VE 46.0 48.0 51.0 52.1 54.0 52.0 59.0 83.2 88.4 59.0 80.0 81.5 71.0 69.2 58.7 61.6 64.0 61.4 54.6 58.8 58.0 Least square line Find : Sxx , Syy'sxy, Is a, b, y = atbxk