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Goal Seek or Solver to Solve for two Unknows?

Goal Seek or Solver to Solve for two Unknows?

(OP)
Hi,

I am trying to figure out if Goal Seek or Solver would be the most appropriate to find two values (Qd for LRB & Qd for NR) that when they are multiplied by a desired value (8 and 24,respectively) would give me another desired value (665.1). Please see attach excel spreadsheet for what I am trying to do.

(8)(Qd for LRB) + (24)(Qd for NR) = 665.1

Really appreciate your help in your guidance on how to accomplish this.

Thanks

RE: Goal Seek or Solver to Solve for two Unknows?

I'm almost certainly missing something here, but it looks like all you are trying to do is solve a single equation for two unknowns.  If so, there is an infinity of possible answers.  You need to introduce another equation, converting the problem to two equations for two unknowns.  Or you need to introduce some sort of optimisation requirement, such as that you require the sum of (Qd for LRB) and (Qd for NR) to be a minimum.

Or you need to explain your requirements in a bit more depth.

RE: Goal Seek or Solver to Solve for two Unknows?

You need at least one more constraint. At the moment there are an infinite number of equally valid solutions.

Doug Jenkins
Interactive Design Services
http://newtonexcelbach.wordpress.com/

RE: Goal Seek or Solver to Solve for two Unknows?

As the others posted, you have an infinite number of results. Actually, the formula you've posted results in a line:
Qd for NR = (665.1 - 8(Qd for LRB))/24
This result in a line with Qd for NR ranging from 0 to 27.7125 and Qd for LRB ranging from 83.1375 to 0 (if we're only looking at the cases where both Qd's aren't negative).

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