function b=xia525(n);
x=[60 70 80 90 100 110 120 130 140 150 160 170];
y=[6.13 7.90 9.99 12.15 15.02 17.50 20.92 26.86 31.11 38.85 47.25 55.05];
plot(x,y,'*b');
hold on
[a,b]=polyfit(x,y,n);
X=linspace(60,170,100);
Y=polyval(a,X);
plot(X,Y,'r');