Edexcel S1 2009 January — Question 3

Exam BoardEdexcel
ModuleS1 (Statistics 1)
Year2009
SessionJanuary
TopicDiscrete Probability Distributions
TypeFind cumulative distribution F(x)

3. When Rohit plays a game, the number of points he receives is given by the discrete random variable \(X\) with the following probability distribution.
\(x\)0123
\(\mathrm { P } ( X = x )\)0.40.30.20.1
  1. Find \(\mathrm { E } ( X )\).
  2. Find \(\mathrm { F } ( 1.5 )\).
  3. Show that \(\operatorname { Var } ( X ) = 1\)
  4. Find \(\operatorname { Var } ( 5 - 3 X )\). Rohit can win a prize if the total number of points he has scored after 5 games is at least 10. After 3 games he has a total of 6 points. You may assume that games are independent.
  5. Find the probability that Rohit wins the prize.