Returns the inverse of the normal cumulative distribution for the specified mean and standard deviation.
Syntax
NORM.INV(probability,mean,standard_dev)
The NORM.INV function syntax has the following arguments:

Probability Required. A probability corresponding to the normal distribution.

Mean Required. The arithmetic mean of the distribution.

Standard_dev Required. The standard deviation of the distribution.
Remarks

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

If probability <= 0 or if probability >= 1, NORM.INV returns the #NUM! error value.

If standard_dev ≤ 0, NORM.INV returns the #NUM! error value.

If mean = 0 and standard_dev = 1, NORM.INV uses the standard normal distribution (see NORMS.INV).
Given a value for probability, NORM.INV seeks that value x such that NORM.DIST(x, mean, standard_dev, TRUE) = probability. Thus, precision of NORM.INV depends on precision of NORM.DIST.
Example
Copy the example data in the following table, and paste it in cell A1 of a new Excel worksheet. For formulas to show results, select them, press F2, and then press Enter. If you need to, you can adjust the column widths to see all the data.
Data 
Description 

0.908789 
Probability corresponding to the normal distribution 

40 
Arithmetic mean of the distribution 

1.5 
Standard deviation of the distribution 

Formula 
Description 
Result 
=NORM.INV(A2,A3,A4) 
Inverse of the normal cumulative distribution for the terms above (42) 
42.000002 