F.INV.RT function
Returns the inverse of the (righttailed) F probability distribution. If p = F.DIST.RT(x,...), then F.INV.RT(p,...) = x.
The F distribution can be used in an Ftest that compares the degree of variability in two data sets. For example, you can analyze income distributions in the United States and Canada to determine whether the two countries have a similar degree of income diversity.
Syntax
F.INV.RT(probability,deg_freedom1,deg_freedom2)
The F.INV.RT function syntax has the following arguments:

Probability Required. A probability associated with the F cumulative distribution.

Deg_freedom1 Required. The numerator degrees of freedom.

Deg_freedom2 Required. The denominator degrees of freedom.
Remarks

If any argument is nonnumeric, F.INV.RT returns the #VALUE! error value.

If probability < 0 or probability > 1, F.INV.RT returns the #NUM! error value.

If deg_freedom1 or deg_freedom2 is not an integer, it is truncated.

If deg_freedom1 < 1, or deg_freedom2 < 1, F.INV.RT returns the #NUM! error value.

If deg_freedom2 < 1 or deg_freedom2 ≥ 10^10, F.INV.RT returns the #NUM! error value.
F.INV.RT can be used to return critical values from the F distribution. For example, the output of an ANOVA calculation often includes data for the F statistic, F probability, and F critical value at the 0.05 significance level. To return the critical value of F, use the significance level as the probability argument to F.INV.RT.
Given a value for probability, F.INV.RT seeks that value x such that F.DIST.RT(x, deg_freedom1, deg_freedom2) = probability. Thus, precision of F.INV.RT depends on precision of F.DIST.RT. F.INV.RT uses an iterative search technique. If the search has not converged after 64 iterations, the function returns the #N/A error value.
Example
The example may be easier to understand if you copy it to a blank worksheet.
How do I copy an example?

Select the example in this article.
Important Do not select the row or column headers.
Selecting an example from Help

Press CTRL+C.

In Excel, create a blank workbook or worksheet.

In the worksheet, select cell A1, and press CTRL+V.
Important For the example to work properly, you must paste it into cell A1 of the worksheet.

To switch between viewing the results and viewing the formulas that return the results, press CTRL+` (grave accent), or on the Formulas tab, in the Formula Auditing group, click the Show Formulas button.
After you copy the example to a blank worksheet, you can adapt it to suit your needs.

