Quadratic Transformations urgent

(Angry)
I need a little help with this problem...

Number of coputers produced-Profit
50---------------------------$5100
100--------------------------$5600
150--------------------------$1100

A-Find a quadratic function that describes the profit as a function of the number of computers produced.

B-Predict the number of computers that need to be produced to maximize the profit.

C-Predict the max profit, assuming that all business conditions stay the same.

For a i have -1.2x^2+189.7+-1390.... i dont know if its right

And for b i found 79 computers....

and for c i found $6107.1

i dont think this makes since... this would mean that between 50-100 it would have hit its max and dropped

I get ...



max profit at computers

Thanks! (Clapping) that makes more sense, i must have had rounded somethin wrong. or wasnt supposed to. But may i ask how did you get the equation?

quadratic regression on a TI-84 calculator.

oh ok i think i got it now....so i enter data in to list. and quadreg it? and im on ti-83 would that matter?

TI-83 does it the same way.

k thanks agn i appreciate it