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Excel functions:
Relationship: Percentile amd Quatile
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Binomial Distribution:
The binomial distribution applies in the following situation:
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a) The outcome of any trial can only take on two possible values, say success and
failure;
b) There is a constant probability p of success on each trial;
c) The experiment is repeated n times (i.e. n trials are conducted);
d) The trials are statistically independent (i.e. the outcome of past trials does not
P( x ) 
n!
p x ( 1  p )n x
x! ( n  x )!
affect subsequent trials); then if x equals the number of successes in the n trials, we
have:
for x = 0, 1, 2, …… n.
EXCEL
=binom.dist(x, n, p, condition),
where x is the value of interest, n is the number of trials, p is the probability of success and
condition is either “false” or “true”.
If you specify the following command
=binom.dist(3, 10, .50, false),
then EXCEL will compute the probability that x = 3.
If you use the command,
=binom.dist(3, 10, .50, true),
then Excel will compute the probability that x  3 . In other words EXCEL will accumulate the
probabilities for x = 0, x = 1, x = 2, and x = 3 and report the total.
Poisson Distribution
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POISSON DISTRIBUTION
where, just as in the case of the binomial distribution, a condition of ‘false’ gives us the
probability of x , and a condition of ‘true’ gives us the probability of being less than or equal to
x.
In this case we want the probability of 3 or anything more extreme, that is the
probability of three or more. We can find,
P ( x  2 )  POISSON ( 2 ,1 , true )  .919699
P ( x  3 )  1  P ( x  2 )  1  .919699  .080311
so that,
which is not rare by the usual standards of .05 or .01.
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Normal distribution: