idata[1]=Import["/Users/troyday/Desktop/Untitled Set 1.txt","Table"];
idata[2]=Import["/Users/troyday/Desktop/Untitled Set 2.txt","Table"];
idata[3]=Import["/Users/troyday/Desktop/Untitled Set 3.txt","Table"];
idata[4]=Import["/Users/troyday/Desktop/Untitled Set 4.txt","Table"];

data[1]=Table[{idata[1][[i,1]],((idata[1][[i,2]])/2)},{i,1,Length[idata[1]]}]
data[2]=Table[{idata[2][[i,1]],((idata[2][[i,2]])/2)},{i,1,Length[idata[2]]}]
data[3]=Table[{idata[3][[i,1]],((idata[3][[i,2]])/2)},{i,1,Length[idata[3]]}]
data[4]=Table[{idata[4][[i,1]],((idata[4][[i,2]])/2)},{i,1,Length[idata[4]]}]

Table[line[i] = Fit[data[i], {1,x},x],{i,1,4}]

l1=Plot[line[1],{x,10,21},PlotStyle->Red]
l2=Plot[line[2],{x,10,27},PlotStyle->Blue]
l3=Plot[line[3],{x,10,21},PlotStyle->Green]
l4=Plot[line[4],{x,7,24},PlotStyle->Yellow]

dataplot1=ListPlot[data[1],PlotStyle->Red]
dataplot2=ListPlot[data[2],PlotStyle->Blue]
dataplot3=ListPlot[data[3],PlotStyle->Green]
dataplot4=ListPlot[data[4],PlotStyle->Yellow]

Show[dataplot1,dataplot2,dataplot3,dataplot4,l1,l2,l3,l4,PlotRange->{{5,28},{0,2.1}},Axes->False,Frame->True,FrameLabel->{"Time (days)","Tumor radius (cm)"},LabelStyle->Directive[FontSize->14]]

Export["1.eps",%22,"EPS"]

Graphics3D[Sphere[{0,0,0},1]]

(4/3) π (r^3)

Manipulate[Graphics3D[Sphere[{0,0,0},r],PlotRange->{{-2,2},{-2,2},{-2,2}}],{r,.1,2}]

4 π (r^2)

(4/3) π (r^3)

s==4 π ((((d/2)))^2)

v==(4/3) π ((((d/2)))^3)

dn/dt=k S

Solve[n==(4/3) π ((((d/2)))^3),d]

Simplify[4 π ((((((n^(1/3)) ((((6/π)))^(1/3)))/2)))^2)]

Simplify[DSolve[n'[t]==a ((n[t])^(2/3)),n[t],t]]

ds/dt

D[((n[t])^(2/3)),t]

((2 n'[t])/((1/27) (a t+C[1])))

a t==Log[(4/3) π]+3 Log[ ((d/2))]

suppose

suppose dV/dt = k V

d

suppose dV/dt = k A

d