OCR MEI Further Statistics A AS 2019 June — Question 1

Exam BoardOCR MEI
ModuleFurther Statistics A AS (Further Statistics A AS)
Year2019
SessionJune
TopicDiscrete Probability Distributions
TypeSimple algebraic expression for P(X=x)

1 The discrete random variable \(X\) has probability distribution defined by $$\mathrm { P } ( X = r ) = k \left( r ^ { 2 } + 3 r \right) \text { for } r = 1,2,3,4,5 \text {, where } k \text { is a constant. }$$
  1. Complete the table below, using the copy in the Printed Answer Booklet giving the probabilities in terms of \(k\).
    \(r\)12345
    \(\mathrm { P } ( X = r )\)\(4 k\)\(10 k\)
  2. Show that the value of \(k\) is 0.01 .
  3. Draw a graph to illustrate the distribution.
  4. Describe the shape of the distribution.
  5. Find each of the following.
    • \(\mathrm { E } ( X )\)
    • \(\operatorname { Var } ( X )\)