interpolation of numbers

[Tom]

trying to set up a program/function that involves
interpolating numbers.

If a house has 1,115sf what is the price for new
construction if a 1,000sf house costs $50 per sf and a
1,200sf house cost $48.50 per sf.

I am trying to find a quicker way. Please help

 

[Dan E]

Tom,

This is interpolation, but . . .

In A1 "1000" in B1 "50.00"
In A2 "1200" in B2 "48.50"
In A3 "1115" and in B3:
=((A3-A1)/(A2-A1))*(B2-B1)+B1

Then you can just change the 1115 to any number...

Dan E

 

[mlindsay]

Have you tried FORCAST()?