WOOD STRENGTH The data show how the strength of Douglas fir wood is related to the percent moisture in the wood. The strength value for wood with 2% moisture is defined to be 1. All other strength values are relative to this value. (For example, wood with 4% moisture is 97.9% as strong as wood with 2% moisture.) Use the quadratic regression feature of a graphing calculator to find the best-fitting quadratic model for the data. Percent moisture, to 2 4 6 B 10 Strength, 5 1 I 0.979 . 0.850 0.774 0.714 Percent moisture. to 12 14 16 is ' 20 Strengths ' 0.543 0.589 ' 0.535 0.494 , 0.458