A-level Mathematics/MEI/S1/Discrete Random Variables

Discrete Random Variables edit

Discrete random variables are the models for the probabilities of particular results. They are represented by the notation,   (Where P is the probability of the Discrete Random Variable, X , taking on the result, R.). A discrete random variable can only take on the values r1,r2,r3...rn with the probabilities p1, p2, p3...pn respectively. Discrete random variables allow us to produce a Discrete Frequency Distribution. Discrete meaning that the value of the results can only take on positive whole integers. In S1, Discrete distributions are limited to a finite number of outcomes.

Exemplar Question edit

Questions often involve working with algebra in order to find the probabilities, in OCR(MEI), you will often have to work out the value of k in order to work out the probabilities.

The probability distribution of a discrete random variable, X, is given by

  

Find the value of k and tabulate the probability distribution.

To find the value of k, we need to tabulate our probabilities and substitute the values of R into the discrete random variable, X.

    R || 2 | 4 | 6 | 8 ||
p(x=R)||