3rd degree polynomial interpolation in functions

How can I find "y" at "x=28" with 3rd degree?

x y

0 0

10 0.2

15 0.5

20 0.9

22.5 1.2

25 1.6

30 2.2

35 3.1

40 4.1

45 5.2

50 6.5

75 13.9

100 24.9

150 58.3

200 97.6

Answer 1

[Michael Madelaire]

Please do not send your data in like that. I have to copy it in some how and now it is just ugly...

% Define x
x = [0
10
15
20
22.5
25
30
35
40
45
50
75
100
150
200];

% Define y
y = [0
0.2
0.5
0.9
1.2
1.6
2.2
3.1
4.1
5.2
6.5
13.9
24.9
58.3
97.6
];

% Make fit
degree = 3;
fit = polyfit(x,y,degree);
x_fit = 0:0.01:200;
y_fit = polyval(fit, x_fit);

% Illustrate fit
figure;
plot(x,y);
hold on;
plot(x_fit, y_fit);
grid on;
xlabel('x');
ylabel('y');
legend('Data', 'Polyfit', 'Location', 'best');
title(sprintf('at x = 28 y is %.2f',polyval(fit,28)))

[Utku Palakci]

My apologies and thank you so much.