You manufacture WIDGETs.  Your old machine broke.
You can buy Machine #1 for $ 5000.  Using machine #1, each widget will cost $ 10 to make.
You can buy Machine #2 for $ 2000.  Using machine #2, each widget will cost $ 15 to make.
I would like to determine the breakeven point for A and B using TWO different methods.
On sheet1, we will use GOAL-SEEK.  On sheet2, we will use graphs.
Here is an outline for sheet1:
| A | B | 
| # of units |   | 
| Cost to make B2 units using machine #1 |   | 
| Cost to make B2 units using machine #2 |   | 
| Breakeven Point |   | 
|   |   | 
Hint: BEP is where both costs are equal.  In general, when P=Q, then P-Q = 0.
On sheet2, create the following grid
| A | B | C | D |   | 
| # units | Machine #1 cost | Machine #2 cost | Which is cheaper |   | 
| 300 |   |   |   |   | 
| 400 |   |   |   |   | 
| 500 |   |   |   |   | 
| 600 |   |   |   |   | 
| 700 |   |   |   |   | 
| 800 |   |   |   |   | 
Compute the cost to produce 300 units using machine #1 and then by machine #2, and using an =IF statement, tell me which machine is cheaper.
Do the same for 400, 500, 600, 700, 800 units.
As you can see, #2 is cheaper for smaller quantities and #1 is cheaper for larger quantities.
Please create a line graph showing the two costs intersecting.  Please have quantity as the x axis and dollars as the y axis.