Discrete random variables are the models for the probabilities of particular results. They are represented by the notation, P ( X = R ) {\displaystyle P(X=R)} (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. 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 P ( X = R ) = k r 8 R = 2 , 4 , 6 , 8. {\displaystyle P(X=R)={\frac {kr}{8}}R=2,4,6,8.} 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)|| k 2 8 {\displaystyle {\frac {k2}{8}}}
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