# Excel NORM.INV Function

*probability*- The probability of an event occurring below a threshold.*mean*- The mean of the distribution.*standard_dev*- The standard deviation of the distribution.

The NORM.INV function returns the inverse of the normal cumulative distribution. Given the probability of an event occurring below a threshold value, the function returns the threshold value associated with the *probability.* For example, NORM.INV(0.5, 3, 2) returns 3 since the probability of an event occurring below the *mean* of the distribution is 0.5. Note, the area under a normal distribution within an interval corresponds to the probability of an event occurring within that interval.

=NORM.INV(0.5,3,2 )// Returns 3

Let's look at another example using the same normal distribution defined by a mean of 3 and *standard deviation* of 2.

=NORM.INV(0.84134,3,2)// Returns 5

In this case, the threshold corresponding to the *probability* of 0.84134 is equal to 5. In other words, the probability of an event occurring below 5 for this normal distribution is equal to 0.8413.

#### Notes

- The
*mean*describes the center or "balancing point" of the normal distribution. - The
*standard deviation*describes the shape of the bell-shaped curve. - Valid
*probability*input to the function is within the range (0,1), excluding 0 and 1.

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