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Bernoulli Trials -
Binomial Probability Distribution

The formula used with Bernoulli trials computes the binomial probability of obtaining
exactly "r" events in "n" trials: 

2

  n = number of trials
  r = number of specific events you wish to obtain
  p = probability that the event will occur
  q = probability that the event will not occur
        (q = 1 - p, the complement of the event)

If you enter the formula directly on the home screen, be careful to use parentheses when entering the exponent of  n - r  (or do the subtraction mentally and enter your calculation).

Consider a problem where
n
= 6, r = 3, and p = 50%
(so, p = .5 and q = .5, where  q = 1 - p)

(Remember, the function nCr is found under
MATH PRB #3 nCr
and requires that the first value, n, be entered
before the function is called.)

2


The easiest way to utilize the calculator to solve this formula is to engage the binompdf function:

binompdf(

 binomial distribution probability density function, which is:
   3  where 4
  (When using this built-in function there is no need to
    type in the formula - YEA!!)


Consider, again, a problem where
n
= 6, r = 3, and p = 50%

(Remember, the function binompdf is found under
DISTR (2nd VARS), arrow down to #0 binompdf
and the parameters are: 
binompdf (number of trials, probability of occurrence, number of specific events)

5

 

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