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\begin{aligned}y &=\frac{105.7379526}{1+6.88328979 e^{-0.2595440013 x}} & & \text { Use the regression model found in part (a). } \\&=\frac{105.7379526}{1+6.88328979 e^{-0.2595400013(18)}} & & \text { Substitute } 18 \text { for } x . \\& \approx 99.3 & & \text { Round to the nearest tenth }\end{aligned}