Returns the cumulative beta probability density function. The beta distribution is commonly used to study variation in the percentage of something across samples, such as the fraction of the day people spend watching television.
X is the value between A and B at which to evaluate the function.
Alpha is a parameter of the distribution.
Beta is a parameter of the distribution.
A is an optional lower bound to the interval of x.
B is an optional upper bound to the interval of x.
If any argument is nonnumeric, BETADIST returns the #VALUE! error value.
If alpha ≤ 0 or beta ≤ 0, BETADIST returns the #NUM! error value.
If x < A, x > B, or A = B, BETADIST returns the #NUM! error value.
If you omit values for A and B, BETADIST uses the standard cumulative beta distribution, so that A = 0 and B = 1.
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