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  • Perplex
    IB Math AASL
    /
    Distributions & Random Variables
    /

    Binomial Distribution

    Edit
    Binomial Distribution

    Binomial Distribution

    Concept of the binomial distribution, binomial PDF and CDF, expectation and variance of binomial distribution

    Want a deeper conceptual understanding? Try our interactive lesson! (Plus Only)

    Exercises

    No exercises available for this concept.

    Key Skills

    The Concept of a Binomial Distribution
    SL 4.8

    The binomial distribution models situations where the same action is repeated multiple times, each with the same chance of success. It has two key numbers: the number of attempts (n) and the probability of success in each attempt (p).


    If a random variable X follows a binomial distribution, we write X∼B(n,p).

    Binomial PDF with calculator
    SL 4.8

    The binomial probability density function (aka pdf) is a function that models the likelihood of obtaining k successes from n trials where the likelihood of success of each trial is p. We calculate the probability of exactly k successes in n trials, P(X=k), using the calculator's binompdf function.


    Press 2nd → distr → binompdf(. Once in the binompdf function, write your n value after "trials," your p value after "p," and your k value after "x value." Then hit enter twice and the calculator will return the probability you are interested in.


    The distr button is located above vars . Once in the distr menu, you can also click alpha → A to navigate to the binompdf function.

    Binomial CDF with Calculator
    SL 4.8

    The binomial cumulative density function tells us the probability of obtaining k or fewer successes in n trials, each with a likelihood of success of p. We calculate the probability of less than or equal to k successes in n trials, P(X≤k), using the calculator's binomcdf function.


    Press 2nd → distr → binomcdf(. Once in the binomcdf function, write your n value after "trials," your p value after "p," and your k value after "x value." Then hit enter twice and the calculator will return the probability you are interested in.


    The distr button is located above vars . Once in the distr menu, you can also click alpha → B to navigate to the binomcdf function.

    Expectation and Variance of Binomial Distribution
    SL 4.8

    If X∼B(n,p), then

    E(X)=np📖

    and

    Var(X)=np(1−p)📖