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  • is the value for which distribution is evaluated.
  • is the mean.
  • is the standard deviation.


  • This function gives the value of the normal probability distribution.
  • It is the continuous probability distribution.
  • The normal distributions are a very important class of statistical distributions.
  • All normal distributions are symmetric and have bell-shaped density curves with a single peak.
  • The term bell curve is used to describe the mathematical concept called normal distribution.
  • It is also called as Gaussian distribution.
  • The Normal Distribution has: mean = median = mode
  • i.e., This distribution is symmetry about the center.
  • Half of values less than the mean and half of values greater than the mean.
  • In a normal distribution the probability values are satisfying the following conditions:
 1. The total area under the curve is equal to 1 (100%) 
 2. About 68% of the area under the curve falls within 1 standard deviation.
 3. About 95% of the area under the curve falls within 2 standard deviations.
 4. About 99.7% of the area under the curve falls within 3 standard deviations. 
  • In a normal distribution the mean =0 and standard deviation =1,then the distribution is called the standard normal distribution or the unit normal distribution, and a random variable with that distribution is a standard normal deviate.
  • It is the only absolutely continuous distribution.
  • A normal distribution is calculated by :

where is the mean and is the standard deviaton of the distribution.


  1. =NORMALDISTRIBUTED(250,255,2.5) = 748.545737759758,417.93831835416444,-92.67846228553037,etc
  2. =NORMALDISTRIBUTED(30,36,20.9) = 7.937852412035841,10.385286729354199,83.54572095198611 etc.

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