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WEIBULL

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Returns the Weibull distribution. Use this distribution in reliability analysis, such as calculating a device's mean time to failure.

Syntax

WEIBULL ( x , alpha , beta , cumulative )

X is the value at which to evaluate the function.

Alpha is a parameter to the distribution.

Beta is a parameter to the distribution.

Cumulative determines the form of the function.

Remarks

  • If x, alpha, or beta is nonnumeric, WEIBULL returns the #VALUE! error value.

  • If x < 0, WEIBULL returns the #NUM! error value.

  • If alpha 0 or if beta 0, WEIBULL returns the #NUM! error value.

  • The equation for the Weibull cumulative distribution function is:

    Cc723032.ZA060512611033(en-us,TechNet.10).gif

  • The equation for the Weibull probability density function is:

    Cc723032.ZA060512621033(en-us,TechNet.10).gif

  • When alpha = 1, WEIBULL returns the exponential distribution with:

    Cc723032.ZA060512631033(en-us,TechNet.10).gif

Example

X

Alpha

Beta

Formula

Description (Result)

105

20

100

=WEIBULL([X],[Alpha],[Beta],TRUE)

Weibull cumulative distribution function for the specified arguments (0.929581)

105

20

100

=WEIBULL([X],[Alpha],[Beta],FALSE)

Weibull probability density function for the specified arguments (0.035589)