A Level Maths Notes: S1 – The Binomial Distribution
The name “The Binomial Distribution” is derived from the binomial expansion, because if you use the formula for binomial expansion,
![]()
you can substitute
and
and
then the probability of obtaining
successes
in
attempts
is given by the
th
term![]()
There are three conditions necessary for the binomial to be a possible distribution.
is
a fixed number. There are
trials
or attempts.
is
fixed throughout the process.
Each trial is independent of any other trial.
The notation for the Binomial distribution is![]()
Example: A fair dice is thrown 10 times. Find the probability of
a)Throwing 3 sixes.
b)Throwing at most 1 six.
c)Throwing at least 1 six.
a)The probability of throwing a six is
to
4dp.
b)
to
4 dp.
c)
to
4 dp.
Intuitively, if
attempts
take place and the probability of success is
the
expected number of successes is![]()