Page 29 - Reference Guide For Foreign Pharmacy Licensing Exam Theory

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The coefficient of variation or relative variation can be calculated by the following equation:

SD
Sx =
√n

Where SX = Standard error of mean,
SD = Standard variation and
n = Number of observation.

Example: If the SD of an individual value is 2, the standard error of means of size 4 is:

2
Sx =
√4

Sx = 1

The Binomial and Normal Distribution

The Binomial Distribution: It is applicable in data where one of two mutually exclusive and independent
outcomes is possible as a result of a single observation or experimental trial.

For example, tossing a coin will bring only one outcome at a time, tail or head.

The probability of success in n binomial trials can be calculated by the following equation:

n
x n−x
P(x) = ( ) P q
x

n
Where ( ) = n !
x x ! (n−x) !

p = probability of success ( p + q = 1) and
q = probability of failure.

Example: Calculate the probability of success that 3 or less of 6 patients will be cured if the probability of
cure of an individual patient is 0.8 or 80%.

6 3 3
P(3) = ( ) (0.8) (0.2) where (p + q = 1)
3

6
P(3) = 6 x 5 x 4x 3 x 2 x1 x 0.512 x 0.008 where ( ) = 6 ! = 6 x 5 x 4x 3 x 2 x1
(3 x 2 x 1)(3 x2 x 1) 3 3 ! (6−3) ! (3 x 2 x 1)(3 x2 x 1)

P(3) = 0.082

The probability (p) of exactly 3 cures from 6 patients is 0.082 or 8.19%.

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