# Find the equation used in this calculator

• Sep 12th 2011, 06:10 AM
Jabo
Find the equation used in this calculator
Hey guys

This has been really bugging me as I can't figure out how to do it. I've just completed 1st year of my motorsport design engineering degree course so it shouldn't be much of a problem!

Alas...

We have these numbers which represent BHP and weight, inputted into a calculator which give an output which supposedly represents a 0-60mph time. I want to figure out what equation is being used, mainly for fun as it's annoying me that I can't figure it out (Angry)

Here is the data we have

BHP, Weight, 0-60

500, 1000, 2.9
600, 1000, 2.9
200, 1000, 4.8
323, 1356, 4.5
223, 1256, 5.7

I have more data if it's needed.
How can I go about coming up with the equation for these outputs?

Thanks in advance :)
• Sep 12th 2011, 02:08 PM
pickslides
Re: Find the equation used in this calculator
Inputting your data into ms-excel and using the regression function in the data analysis suite I get,

Time = -0.006091194 BHP + 0.001961836 Weight + 4.27146484

More data would be helpful to get a better fit as the p-values for the regression parameters are not all significant.
• Sep 12th 2011, 02:55 PM
Jabo
Re: Find the equation used in this calculator
More data:

197 bhp, 1150 weight, 5.8 time
402 bhp, 905 weight, 3.1 time
373 bhp, 961 weight, 3.3 time
665 bhp, 1008 weight, 2.8 time
90 bhp, 800 weight, 10.9 time

Thanks for the help so far mate. More data?
• Sep 12th 2011, 03:00 PM
pickslides
Re: Find the equation used in this calculator
Give me all the data you have, but in the format in post #1, just the commas in between.
• Sep 12th 2011, 03:06 PM
Jabo
Re: Find the equation used in this calculator
500, 1000, 2.9
600, 1000, 2.9
200, 1000, 4.8
323, 1356, 4.5
223, 1256, 5.7
197, 1150, 5.8
402, 905, 3.1
373, 961, 3.3
665, 1008, 2.8
90, 800, 10.9
800, 1150, 2.7
264, 1439, 5.4
148, 1301, 8.5
128, 1287, 9.8
119, 1244, 10.0

All I've got
• Sep 12th 2011, 03:42 PM
pickslides
Re: Find the equation used in this calculator
No worries, here is the output,

Parameter \$\displaystyle ~~~~~~~~~~\$ Coefficients \$\displaystyle ~~~~~~~~\$P-value
Intercept 8.856424987 0.020317672
X Variable 1 -0.010798898 0.0004769
X Variable 2 0.000272509 0.920580742
• Sep 12th 2011, 04:03 PM
Jabo
Re: Find the equation used in this calculator
Ok cheers mate. I'm going to run some more numbers through the formula and see how it works out. Hopefully the 0.92 p value doesn't mean that times are going to be too far out from the original calculator.
• Sep 12th 2011, 04:15 PM
Jabo
Re: Find the equation used in this calculator
Doesn't work too well :-/ e.g. the 197, 1150 car gives a time of 7.04s, it should be 5.8s :(
• Sep 12th 2011, 04:54 PM
Jabo
Re: Find the equation used in this calculator
The 119, 1244 inputs give 7.9 when it should be 10.0
What do you recommend? More data?