The Excel function NORM.DIST is designed to calculate the probability that a given value will fall under a normal distribution curve defined by specific parameters. This functionality is essential for statistical analysis, enabling users to understand the likelihood of outcomes for datasets assumed to follow a normal distribution.

Syntax

NORM.DIST(x, mean, standard_dev, cumulative)

• x: The value for which you want the distribution.
• mean: The arithmetic mean of the distribution.
• standard_dev: The standard deviation of the distribution.
• cumulative: A logical value indicating whether to calculate the cumulative distribution function (TRUE) or the probability density function (FALSE).

Example #1

=NORM.DIST(10, 5, 2, TRUE)

In this example, the function calculates the cumulative probability that a value less than or equal to 10 occurs in a normal distribution with a mean of 5 and a standard deviation of 2, resulting in a value of approximately 0.9772.

Example #2

=NORM.DIST(3, 0, 1, FALSE)

This function computes the probability density for the value 3 under a standard normal distribution (mean 0, standard deviation 1). The result, in this case, would be approximately 0.1413, indicating the likelihood of observing this exact value.

Example #3

=NORM.DIST(7, 4, 1.5, TRUE)

Here, the function assesses the cumulative probability that values are less than or equal to 7 in a normal distribution where the mean is 4 and the standard deviation is 1.5. The result yields approximately 0.9525, showing a high probability of such an occurrence.

Error handling

• VALUE! This error arises if any of the arguments are non-numeric. Ensure that x, mean, and standard_dev are valid numbers.
• NUM! This error indicates an invalid input, particularly if standard_dev is less than or equal to zero. The standard deviation must be positive for the normal distribution.
• NAME? This occurs if the function is written incorrectly or the Excel version does not support it. Verify the function name and syntax.

Conclusion

The NORM.DIST function in Excel is a powerful tool for statistical analysis, allowing users to efficiently determine the probability related to normally distributed data. Understanding its syntax and error messages helps leverage its use for various applications in analytics, finance, and research.