4. An experiment was performed to improve the yield of a chemical process. Four factors were selected, and two replicates of a completely randomized experiment were run. The results are shown in the following table: Treatment Replicate Treatment Replicate Combination Combination II II (1) 90 93 d 98 95 74 78 add 72 76 b 81 85 bd 87 83 ab 83 80 abd 85 86 C 77 78 ed 99 90 ac 81 80 acd 79 75 bc 88 82 bcd 87 84 abc 73 70 abcd 80 80 a Estimate the factor effects. (15 points)