Microsoft Office

Analyzing Data Using Goal Seek and Solver 37
Next, choose Data ➪ Data Tools ➪ What-If Analysis ➪ Goal Seek. Excel displays the Goal Seek dialog box,
shown in Figure 37.2. Completing this dialog box is similar to forming a sentence. You want to set cell C11
to 1800 by changing cell C4. Enter this information in the dialog box either by typing the cell references or
by pointing with the mouse. Click OK to begin the goal-seeking process.
FIGURE 37.2
The Goal Seek dialog box.
In less than a second, Excel displays the Goal Seek Status box, which shows the target value and the value
that Excel calculated. In this case, Excel found an exact value. The worksheet now displays the found value
in cell C4 ($284,779). As a result of this value, the monthly payment amount is $1,800. At this point, you
have two options:
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Click OK to replace the original value with the found value.
Click Cancel to restore your worksheet to the form that it had before you chose the Goal Seek
command.
More about Goal Seeking
Excel can’t always find a value that produces the result that you’re seeking. Sometimes, a solution simply
doesn’t exist. In such a case, the Goal Seek Status box informs you of that fact.
Other times, however, Excel may report that it can’t find a solution, but you’re pretty sure that one exists. If
that’s the case, you can try the following options:
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Change the current value of the By Changing Cell box in the Goal Seek dialog box to a value that
is closer to the solution and then reissue the command.
Adjust the Maximum iterations setting in the Formulas tab of the Excel Options dialog box
(choose Office ➪ Excel Options). Increasing the number of iterations (or calculations) makes
Excel try more possible solutions.
Double-check your logic and make sure that the formula cell does, indeed, depend on the specified
changing cell.
Like all computer programs, Excel has limited precision. To demonstrate this limitation, enter
NOTE
=A1^2 into cell A2. Then, use the Goal Seek dialog box to find the value in cell A1 (which is
empty) that makes the formula return 16. Excel comes up with a value of 4.00002269010434 (you may need
to widen the column to see the complete value), which is close to the square root of 16, but certainly not
exact. You can adjust the precision in the Formulas tab of the Excel Options dialog box (make the Maximum
Change value smaller).
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