1. Some tests were carried out on a newly designed carburetor. Four variables were studied as follows: Variable ABCD Description Spring tension Air gap Aperture Size + low high narrow open small slow large rapid Gas flow rate The immediate objective was to find the effects of these changes on the amount of unburned hydrocarbons in the engine exhaust gas. The following results were obtained from a 24-1 design: Run A B C Unburned hydrocarbons 1 + + + 8.2 2345 17 + 1.7 + 6.2 3.0 + + 6.8 5.0 3.8 8 + 9.3 The researcher wants to find a combination of A, B, C, and D that will minimize the levels of unburned hydrocarbons. Analyze this data using an appropriate modification of Yates' method. Use the results of this analysis to make some recommendations about further experiments that might be conducted