Filling in Information for y values

[joonsays]

Speed Horsepower
20 .5
30 1.7
40 4
50
60
70
80
90
100
110
120 110
130 140
140 170

i was wondering how i can fill in the blanks with excel...i know that if it was a linear slope than it's easy, but this graphed is a curved slope.

[nsv]

Right click on the curve and add a trendline.
As the power demand for typical car velocities grows with the cube of the speed the trendline should not be linear (which is default) but a third degree polynomium. Change that with Edit Trendline.
Also, when editing, add the equation for the polynomium. It looks like:
y = 4.060E-05x3 + 4.343E-03x2 - 2.045E-01x + 2.651E+00
after you have set the format to Scientific, which you must do to get sufficient amount of digits.
Copy the formula into the cells with missing y-values. You will have to adjust it by changing 'x3' to '*A5^3', 'x2' to '*A5^2' and 'x'x to '*A5' (supposing the missing y-value is in B5 and the corresponding x-value in A5).


NSV