data=Import["/Users/troyday/Desktop/GauseData.txt","Table"]

Solve[(64/(1+k))==2.1,k]

ListPlot[data,PlotStyle->{Red,PointSize[.02]}]
Plot[(64/(1+31 Exp[-0.7944 t])),{t,0,16},PlotRange->{0,80},Frame->True,FrameLabel->{"Days","Volume"},LabelStyle->Directive[FontSize->14]]
Show[%,%%]

Export["1.eps",%87,"EPS"]

Plot[(64/(1+31 Exp[-0.7944 t])),{t,0,25}]

D[(64/(1+31 Exp[-0.7944 t])),t]

Plot[{(64/(1+31 Exp[-0.7944 t])),((1576.0896` (E^(-0.7944` t)))/(((1+31 (E^(-0.7944` t))))^2))},{t,0,16},PlotRange->{0,80},Frame->True,FrameLabel->{"Days","Volume"},LabelStyle->Directive[FontSize->14],PlotStyle->{Black,Red}]

Export["1.eps",%327,"EPS"]